>>> TONIGHT, THE DRAMATIC BODY CAM VIDEO OF POLICE TAKING DOWN THE SHOOTER IN A NASHVILLE SCHOOL. THE IMAGES INSIDE THE SCHOOL. POLICE RUNNING TOWARD THE SHOTS, THE OFFICERS ROUNDING THE CORNER IN A BARRAGE OF GUNFIRE. MINUTES EARLIER, THE ATTACKER SHOOTING THROUGH GLASS DOORS AND ENTERING THE SCHOOL, AND THEN ROAMING THE HALLS ARMED WITH RIFLES. POLICE REVEALING TODAY THE SHOOTER WAS BEING TREATED FOR AN EMOTIONAL DISORDER, AND LEGALLY PURCHASED SEVEN GUNS. THE CHILLING MESSAGE THE SHOOTER SENT JUST MINUTES BEFORE THE MASSACRE, AND WHAT WE'RE LEARNING ABOUT THE SIX PEOPLE KILLED, INCLUDING THREE 9-YEAR-OLDS. >>> ALSO TONIGHT, MIKE PENCE ORDERED TO TESTIFY IN THE SPECIAL COUNSEL'S JANUARY 6th INVESTIGATION. WHAT HE MUST DISCLOSE ABOUT HIS CONVERSATION ABOUT DONALD TRUMP. >>> THE NEW BOMB CYCLONE TARGETING THE WEST AND THE URGENT RELIEF EFFORT IN THE SOUTH AFTER THAT DEADLY TORNADO OUTBREAK. OUR TEAM IN THE STORM ZONE WITH FAMILIES WHO HAVE LOST EVERYTHING. >>> THE DEADLY FIRE AT A MIGRANT CENTER NEAR THE U.S.-MEXICO BORDER. DOZENS KILLED. WAS IT STARTED AS A PROTEST? >>> ALLERGY SEASON OFF TO AN EARLY START. WHY IT'S GETTING LONGER AND STRONGER, AND HOW YOU CAN GET RELIEF. >>> AND THE PHOTOGRAPHER WHO TEAMED UP WITH YOUNG ENGINEERS TO KEEP CHASING HIS PASSION. HE IS INSPIRING AMERICA. >> Announcer: THIS IS "NBC NIGHTLY NEWS" WITH LESTER HOLT. >> GOOD EVENING, EVERYONE, AND WELCOME. AS FAMILIES GRIEVE THE LIVES OF SIX PEOPLE MURDERED IN A NASHVILLE PRIVATE CHRISTIAN SCHOOL, WE'RE GETTING A CHILLING LOOK INTO THE HEART-POUNDING MOMENTS WHEN THE FIRST RESPONDING POLICE OFFICERS BRAVED GUNFIRE, ENTERED THE SCHOOL, AND ADVANCED FROM ROOM TO ROOM, LOCATING AND FATALLY SHOOTING THE SUSPECT. NEWLY RELEASED VIDEO OF THE ATTACK JUST PART OF A TROVE OF INFORMATION HELPING POLICE PIECE TOGETHER HOW THE SUSPECT PLANNED AND GATHERED WEAPONS FOR THE ATTACK. THE TREATMENT THE SUSPECTS SOUGHT FROM A DOCTOR, AND THE DARK FINAL MESSAGES AUDREY HALE SHARED WITH A FORMER TEAMMATE SHORTLY BEFORE THE SCHOOL ATTACK BEGAN. POLICE SAY THEY HAVE INTERVIEWED THE ATTACKER'S PARENTS WHO SAY THEY WERE UNAWARE HALE HAD AMASSED SEVEN LEGALLY PURCHASED FIREARMS. BUT POLICE STILL NOT PREPARED TO SUGGEST A MOTIVE. LET'S GET LATE DETAILS NOW FROM KATHY PARK IN NASHVILLE. >> MOVE, MOVE! WATCH OUT, WATCH OUT! >> Reporter: CHILLING NEW BODY CAMERA FOOTAGE FROM NASHVILLE POLICE CAPTURE THE SHOOTER'S FINAL MOMENT FOLLOWING A DEADLY RAMPAGE AT A PRIVATE CHRISTIAN ELEMENTARY SCHOOL. OFFICERS RUNNING TOWARDS DANGER, GUNNING DOWN THE HEAVILY ARMED SHOOTER, 28-YEAR-OLD AUDREY HALE, WHO POLICE SAY IDENTIFIED AS TRANSGENDER. >> AUDREY BOUGHT SEVEN FIREARMS FROM FIVE DIFFERENT LOCAL GUN SOURCE HERE LEGALLY. >> Reporter: POLICE SAY HALE USED THREE OF THOSE GUNS IN THE RAMPAGE, KILLING THREE ADULTS AND THREE STUDENTS, ALL 9 YEARS OLD. >> THIS SCHOOL, THIS CHURCH BUILDING WAS A TARGET OF THE SHOOTER. >> Reporter: AUTHORITIES TODAY REVEALING THE SHOOTER'S PARENTS WERE NOT AWARE HALE WAS CURRENTLY IN POSSESSION OF ANY GUN. >> SHE WAS UNDER CARE, A DOCTOR'S CARE FOR EMOTIONAL DISORDER. LAW ENFORCEMENT KNEW NOTHING ABOUT THE TREATMENT SHE WAS RECEIVING, BUT HER PARENTS FELT THAT SHE SHOULD NOT OWN WEAPONS. >> Reporter: THE MORNING OF THE MASS SHOOTING, SURVEILLANCE VIDEO SHOWS HALE BLASTING OUT THE GLASS DOORS TO GET ACCESS INSIDE. VIDEO FROM 10:18 A.M. SHOWS HALE IN THE SCHOOL HALLWAY, HEAVILY ARMED. THEN NEAR THE CHILDREN'S MINISTRY. THE STUNNING BODY CAMERA VIDEO SHOWS THE MOMENT POLICE ARRIVED ON SCENE. >> THE KIDS ARE ALL LOCKED DOWN, BUT WE HAVE TWO KIDS WE DON'T KNOW WHERE THEY ARE. >> GO, GO! >> Reporter: INSIDE THE SCHOOL, SIRENS BLARING. AS OFFICERS GO FROM DOOR TO DOOR. MOMENTS LATER, POLICE CONFRONT THE SHOOTER ON THE SECOND FLOOR. [ GUNSHOTS ] THEN SHOTS FIRED. AND BY 10:27 A.M., POLICE SAY THE SHOOTER WAS DEAD. TONIGHT A MOTIVE UNCLEAR AS AUTHORITIES CONTINUE TO COMB THROUGH CLUES LEFT BEHIND. >> THERE IS SEVERAL DIFFERENT WRITINGS. I HAVE NOT READ THE WHOLE ENTIRE MANIFESTO. OUR TEAM AND THE FBI HAVE BEEN WORKING ON THEM. >> Reporter: THE SHOOTING HITTING TOO CLOSE TO AVERIANNA PATTON, WHO GREW UP WITH HAIL, RECEIVING A WARNING ON INSTAGRAM SOMETHING BAD WAS GOING TO HAPPEN MINUTES BEFORE THE MASSACRE. >> I WROTE BACK AND SAID "AUDREY, YOU HAVE SO MUCH MORE LIFE TO LIVE." WHAT WOULD YOU DO IF YOU WERE SENT A MESSAGE LIKE THAT? I DON'T REALLY KNOW. I SENT THE MESSAGE TO MY DAD. DO YOU THINK I SHOULD SAY SOMETHING TO SOMEBODY? HE SAID YES IN ALL CAPS. THAT'S WHEN I STARTED MAKING CALLS. >> Reporter: BUT HALE'S PLAN WAS ALREADY UNDER WAY. AMONG THE LIVES LOST, SUBSTITUTE TEACHER CYNTHIA PEAK, LONG-TIME CUSTODIAN MIKE HILL, AND KATHERINE KOONCE, HEAD OF THE COVENANT SCHOOL. THE YOUNGEST VICTIMS EVELYN, WILLIAM, AND HALLIE. >> WE'RE ALL ASKING QUESTIONS RIGHT NOW. NO ONE REALLY UNDERSTANDS. >> Reporter: TONIGHT FINDING COMFORT IN FAITH IN A PLACE WHERE STUDENTS SHOULD ALWAYS BE SAFE. >> KATHY JOINS US NOW LIVE FROM NASHVILLE. KATHY, AMAZING HOW FAST THOSE OFFICERS MOVED INTO THE SCHOOL. HOW ARE OFFICIALS ASSESSING THEIR OWN RESPONSE TO THE SHOOTING? >> WELL, LESTER, POLICE CHIEF SAYS THERE IS ALWAYS ROOM FOR IMPROVEMENT, BUT THE PRESIDENT DID REACH OUT TO THE CHIEF AND RESPONDING OFFICERS DIRECTLY AND COMMENDED THEM FOR THEIR QUICK ACTIONS AND BRAVERY. LESTER? >> ALL RIGHT, KATHY PARK, THANK YOU. >>> ALSO DEVELOPING, NBC NEWS HAS LEARNED A FEDERAL JUDGE IS ORDERING FORMER VICE PRESIDENT MIKE PENCE TO TESTIFY TO A GRAND JURY. THE ONE CALL BY THE SPECIAL COUNSEL INVESTIGATING FORMER PRESIDENT TRUMP'S EFFORTS TO OVERTURN HIS ELECTION LAWS. LAURA JARRETT WAS FIRST TO REPORT THIS STORY. LAURA, THIS IS POTENTIALLY A BIG WIN FOR THE SPECIAL COUNSEL. >> IT COULD BE A GAME-CHANGER, LESTER. THE SPECIAL COUNSEL HAS BEEN TRYING FOR MONTHS TO MAKE PENCE TESTIFY ABOUT HIS CONVERSATIONS WITH FORMER PRESIDENT TRUMP IN THE DAYS LEADING UP TO JANUARY 6th. NOW WHILE THE JUDGE DID ACKNOWLEDGE PENCE'S NOVEL CONSTITUTIONAL ARGUMENT THAT HE SHOULD RECEIVE IMMUNITY FROM TESTIFYING GIVEN HIS ROLE AS PRESIDENT OF THE SENATE ON JANUARY 6th, A SOURCE FAMILIAR WITH THE RULING TELLS ME THE JUDGE DECIDED THAT IMMUNITY WOULD NOT PREVENT PENCE FROM TESTIFYING ABOUT ANY ALLEGED ILLEGALITY ON TRUMP'S PART. >> WE'RE GETTING LATE REACTION FROM THE FORMER VP? >> THAT'S RIGHT. SAID HE IS PLEASED WITH THAT RULING OF THE ARGUMENT, ACCEPTING THIS CONSTITUTIONAL ARGUMENT. HE OR TRUMP COULD STILL APPEAL THIS CASE. MEANWHILE, THE TRUMP CAMPAIGN SAYS, QUOTE, THERE IS NO FACTUAL OR LEGAL BASIS OR SUBSTANCE TO THE CASE. THE JUSTICE DEPARTMENT, HOWEVER, DECLINED TO COMMENT. >> LAURA JARRETT, THANK YOU. >>> FOUR DAYS AFTER THOSE DEVASTATING TORNADOES IN MISSISSIPPI, THE RECOVERY EFFORT HAS ONLY JUST BEGUN. AND PERHAPS NOWHERE IS IT MORE CHALLENGING THAN IN ONE SMALL TOWN THAT WAS ALL BUT WIPED OUT. MAGGIE VESPA IS THERE FOR US TONIGHT. >> Reporter: CLEANUP IS UNDER WAY IN ROLLING FORK, MISSISSIPPI. AS FEMA ARRIVED IN THE SMALL TOWN RAVAGED BEYOND RECOGNITION, THE MORRIS FAMILY LOST EVERYTHING. >> ONE MINUTE IT'S STANDING. THE NEXT IT WAS GONE. >> Reporter: BRENDA AND HER FAMILY ARE DIGGING FOR BELONGINGS WHERE THEIR HOME ONCE STOOD, AND BRACING FOR LIFE IN LIMBO. THE FAMILY OF 11 RODE AT THE STORM AT HOME, 10 OF THEM NOW STAYING WITH BRENDA'S SISTER IN A NEARBY TOWN AS A NEPHEW, 8-YEAR-OLD JEREMY RECOVERS IN THE HOSPITAL AFTER SUSTAINING A BRAIN INJURY WHEN THE HOUSE COLLAPSED. >> HE CAN'T TALK RIGHT NOW. BUT HE CAN MOVE HIS LEGS AN HIS ARMS. HE IS COMING ALONG. HE IS GOING TO MAKE IT. >> Reporter: TODAY AFTER FRIDAY'S DEADLY EF-4 TORNADO THAT CLAIMED 22 LIVES ACROSS MISSISSIPPI AND ALABAMA, SURVIVORS ARE BEING POINTED TO A PATCHWORK OF HOTELS AND SHELTERS. AMONG THEM, CHARNISE. >> I'M BLESSED, BUT I CAN'T SAY I'M OKAY MENTALLY. >> Reporter: HER HOME WAS DESTROYED WHEN THE TORNADO TORE THROUGH. SO SHE WENT TO HER MOTHER'S HOUSE, WHERE SHE PLANNED TO STAY WITH HER THREE SONS, BUT THAT HOUSE BURNED DOWN THE NEXT DAY WHEN THE GENERATOR CAUGHT FIRE. NOW THEY'RE ALL AT A HOTEL. >> AS WE PICK UP WHAT WE CAN, RETRIEVE FROM THE STORM, THEY'RE LIKE OKAY, WHEN ARE WE GOING HOME? REFERRING TO THE HOTEL AS HOME. >> Reporter: FEDERAL OFFICIALS ARE ON THE GROUND PUSHING PEOPLE TO SIGN UP FOR DISASTER RELIEF, FUNDS TO HELP WITH EVERYTHING FROM TEMPORARY HOUSING TO REPAIRS, WITH AN ESTIMATED 2,000 HOMES DAMAGED STATEWIDE, ASSESSMENTS WILL TAKE TIME. ATTENTION NOW TURNING TO THE BARE NECESSITIES LIKE POWER AND WATER, OUT SINCE FRIDAY. >> DON'T KNOW WHAT I NEED STILL FOR. OUR WHOLE COMMUNITY IS GONE. WE HAVE NOTHING TO GO TO. WE DON'T KNOW WHAT WE WOULD DO NEXT WEEK. WE JUST DON'T KNOW. >> Reporter: THAT'S A SENTIMENT MANY OF THE PEOPLE I SPOKE WITH ARE FEELING, THAT THE EMERGENCY RELIEF OPTIONS THAT ARE IN PLACE ARE SHORT-TERM. ONE WOMAN TOLD ME A LOCAL OFFICIAL GAVE HER A HOTEL VOUCHER GOOD THROUGH THE WEEKEND. AFTER THAT, SHE HAS NO IDEA WHERE SHE'LL GO. LESTER? >> ALL RIGHT, MAGGIE VESPA, THANK YOU. >>> ON THE OTHER SIDE OF THE COUNTRY, CALIFORNIA JUST CAN'T CATCH A BREAK. IT'S BEING BATTERED TONIGHT BY YET ANOTHER POWERFUL STORM. MIGUEL ALMAGUER IS NEAR SANTA CRUZ ALONG THE COAST. MIGUEL, WHAT'S THE SITUATION THERE? >> WELL, LESTER, TREES ARE DOWN. ROADS ARE FLOODED. MAJOR HIGHWAYS EVEN SHUT DOWN. JUST A SHORT TIME AGO HERE, IT WAS POUNDING RAIN AND THE WINDS WERE REALLY HOWLING. CALIFORNIA HAS ALREADY EXPERIENCED 12 ATMOSPHERIC RIVERS. WE'RE NOW IN THE MIDDLE OF ANOTHER BOMB CYCLONE. WHILE RAIN HAS REALLY BEEN HAMPERING THE STATE FOR THE LAST SEVERAL HOURS, THE CONCERN IS GOING TO BE WINDS. UPWARDS OF 70 MILES PER HOUR OVER THE NEXT 24 TO 48 HOURS. WE COULD EVEN HAVE WATERSPOUTS ALONG THE COAST AND THE RARE TORNADOES LIKE WE SAW LAST WEEK IN CALIFORNIA. ALL OF THIS HAS BEEN A TREMENDOUS IMPACT FOR THE SNOWPACK. WE'RE UPWARDS OF 200% OF AVERAGE. THIS HAS ESSENTIALLY BEEN A DROUGHT-BUSTER, BUT IT'S COME AT A COST, BILLIONS OF DOLLARS IN DAMAGE, AND WE'RE NOT OUT OF THE WOODS YET. LESTER? >> ALL RIGHT. MIGUEL ALMAGUER, THANK YOU. LET'S BRING IN DYLAN DREYER WHO IS TRACKING THIS LATEST STORM. HOW IS THIS GOING THE PLAY OUT? >> WELL, WE'RE GOING TO SEE MORE RAIN, LESTER. IT HASN'T EVEN BEEN A WEEK, AND NOW WE HAVE THE HEAVY RAIN FALLING THROUGH CENTRAL CALIFORNIA. THAT IS GOING TO CONTINUE TO MOVE EASTWARD. UNTIL THEN, WE'RE LOOKING AT SEVERAL MORE INCHES OF HEAVY, HEAVY WIN. WINDS HAVE BEEN GUSTING AS HIGH AS 40 TO 50 MILES PER HOUR WITH THE GROUND SATURATED, THAT INCREASES THE RISK OF POWER OUTAGES WHEN YOU HAVE THOSE POLES STICKING IN THE GROUND THAT IS TOTALLY SATURATED. SO WE'RE LOOKING AT ANOTHER 1 TO 3 INCHES OF RAIN AT LEAST IN THE SAME AREAS THAT HAVE BEEN HARD HIT. THEN YOU GO UP INTO THE MOUNTAINS WHERE IT'S COLD ENOUGH FOR SNOW. WE'RE LOOKING AT ABOUT 3 TO 4 FEET OF SNOW. ALSO WANT TO POINT OUT, THIS IS GOING TO BE THE NEXT STORM SYSTEM THAT IS GOING TO RACE ACROSS THE COUNTRY AND INCREASE OUR SEVERE THREAT FOR FRIDAY IN ORANGE, FROM IOWA, ILLINOIS RIGHT DOWN INTO ARKANSAS AND PARTS OF MISSISSIPPI. WINDS OVER 60 MILES PER HOUR. LARGE HAIL, AND WE COULD SEE MORE TORNADOES OUT OF THIS NEXT STORM ON FRIDAY. >> ALL RIGHT. DYLAN DREYER, THANK YOU SO MUCH FOR THAT. >>> IN FRANCE TODAY, NEW MASS PROTESTS AS HUNDREDS OF THOUSANDS MARCHED IN OPPOSITION TO PRESIDENT EMMANUEL MACRON'S DECISION TO RAISE THE RETIREMENT AGE FROM 62 TO 64. POLICE CLASHED WITH PROTESTERS IN PARIS. THE DEMONSTRATIONS HAVE BEEN GROWING SINCE MACRON PUSHED THE CHANGE THROUGH PARLIAMENT WITHOUT A VOTE. >>> IN MEXICO TONIGHT, JUST ACROSS THE BORDER FROM EL PASO, TEXAS, A SEARCH FOR ANSWERS AFTER A FIRE KILLED DOZENS OF PEOPLE AT A MIGRANT DETENTION CENTER. GABE GUTIERREZ HAS THE LATEST. >> Reporter: ANGUISHED SCREAMS OF DESPERATION FROM A WOMAN SEARCHING FOR HER HUSBAND AFTER A FIRE TORE THROUGH A GOVERNMENT HOLDING CENTER IN CIUDAD JUAREZ IN MEXICO. YOU CAN SEE THIS THE FLAMES IN THE CORNER OF THE SCREAM OF THIS SURVEILLANCE VIDEO OBTAINED BY TELEMUNDO AS THE ROOM BEGINS TO FILL WITH SMOKE. TONIGHT AT LEAST 39 PEOPLE ARE DEAD, ANOTHER 29 INJURED FEARED INJURE AT HOSPITAL. THEY'RE MAINLY FROM CENTRAL AMERICA AND VENEZUELA. MEXICO'S PRESIDENT SAID SOME OF THE MIGRANTS PUT SMALL MATTRESSES AT THE DOOR OF THE FACILITY AND SET THEM ON FIRE IN PROTEST WHEN THEY FOUND OUT THEY'D BE DEPORTED. BUT THE BLAZE, HE SAYS, RAGED OUT OF CONTROL. RELATIVES NOW SAYING SOME OF THE MIGRANTS HAD BEEN ROUNDED UP FROM THE STREETS OF JUAREZ SHORTLY BEFORE THE FIRE, AND THAT THE MEN HAD BEEN KEPT IN CELLS, WHILE WOMEN AND CHILDREN HAD BEEN RELEASED. "DON'T TREAT US LIKE ANIMAL," THIS WOMAN SAYS. IT'S RIGHT BEFORE DAWN, AND THE CONDITIONS HERE ARE MISERABLE. WE VISITED JUAREZ LAST YEAR AS HUGE GROUPS OF MIGRANTS TRIED TO CROSS INTO THE U.S. JUST WEEKS AGO, ANOTHER STORMED THE INTERNATIONAL BRIDGE IN NEIGHBORING EL PASO, TEXAS. TODAY ON CAPITOL HILL, THE HOMELAND SECURITY SECRETARY WAS PRESSED ABOUT HIS BORDER PATROL CHIEF'S RECENT ACKNOWLEDGMENT THAT THE U.S. DID NOT HAVE OPERATIONAL CONTROL OF THE SOUTHERN BORDER. >> WE ARE INTENSELY FOCUSED ON SECURING THE BORDER. >> Reporter: THIS YEAR IS ALREADY ON PACE TO SURPASS LAST YEAR'S RECORD NUMBER OF ILLEGAL BORDER CROSSINGS. AFTER THE FIRE, THE MEXICAN GOVERNMENT NOW SAYS IT WILL PAY FOR THE INJURED MIGRANTS' MEDICAL BILLS. LESTER? >> GABE GUTIERREZ, THANK YOU. >>> IN 60 SECONDS, AN APPEALS COURT REINSTATES THE MURDER CONVICTION OF ADNAN SYED, THE SUBJECT OF A "SERIAL" PODCAST. WHAT IT MEANS. >>> AND A GROWING PROBLEM FOR EMERGENCY >>> BACK NOW WITH A NEW TWIST IN A CASE THAT MADE NATIONAL HEAI >>> BACK NOW WITH A NEW TWIST IN A CASE THAT MADE NATIONAL HEADLINES AFTER IT WAS PROFILED ON THE PODCAST "SERIAL." MARYLAND'S APPELLATE COURT REINSTATING THE MURDER CONVICTION AGAINST ADNAN SYED, WHO SPENT 23 YEARS IN PRISON FOR THE 1999 MURDER OF HIS EX-GIRLFRIEND. THE COURT TODAY ORDERING A NEW HEARING AFTER THE VICTIM'S FAMILY SAID THEY WERE NOT PROPERLY NOTIFIED OF EFFORTS TO FREE SYED LAST YEAR. SYED WAS RELEASED IN OCTOBER AFTER PROSECUTORS SAID NEW DNA TESTS SUPPORTED HIS INNOCENCE. >>> ALSO TONIGHT, THE GROWING PROBLEM FIRST RESPONDERS SAY THEY ARE SEEING ON THE NATION'S ROADWAYS, DISTRACTED DRIVERS, CONGESTED ROADS, AND SOUND-PROOF CARS COSTING THEM PRECIOUS MINUTES AND SECONDS WHEN THEY ANSWER 911 CALLS. HERE IS TOM COSTELLO. >> Reporter: IT'S A DAILY CHALLENGE FOR EMERGENCY RESPONDERS NATIONWIDE. >> BATTALION CHIEF 3 WITH A KNOWN INJURY. >> Reporter: CONGESTION, GRIDLOCK. >> WORKING THE WAY RIGHT AND CUT ALL THE WAY ACROSS. >> Reporter: DRIVERS WHO PANIC OR WON'T BUDGE. >> THE LAST THING YOU WANT TO DO WHEN YOU AN EMERGENCY VEHICLE BEHIND YOU IS JUST STOP. >> Reporter: EVERY CREW WE'VE RODE WITH SAID THEY'VE BEEN ON CALLS WHERE A LIFE COULD HAVE BEEN SAVED HAD THEY ONLY GOTTEN THERE SOONER. NATIONALLY, FIRE AND EMS RESPONSE TIMES AVERAGE 7 TO 8 MINUTES IN CITIES. LONGER IN RURAL AREAS. >> IF SOMEONE IS NOT BREATHING OR THEIR HEART IS NOT WORKING, MINUTES ARE CRITICAL IN THAT KIND OF SITUATION. >> Reporter: ONE BIG PROBLEM, DRIVERS TODAY ARE OFTEN COCOONED IN MODERN CARS THAT ARE DESIGNED TO KEEP OUTSIDE NOISE OUTSIDE. >> THEY'RE BETTER INSULATED. THEY'RE BETTER NOISE DAMPENING. >> Reporter: AND A FAST-MOVING AMBULANCE OR FIRE ENGINE MAY BE MOVING FASTER THAN ITS SIREN. YOU SEE THAT FIRE TRUCK BEHIND ME? I'M GOING 40 MILES PER HOUR RIGHT NOW. I'VE GOT THE RADIO ON, THE AIR ON. AND I'M ONLY RIGHT NOW HEARING THE SIREN. MANY DEPARTMENTS NOW RUN TWO SIRENS SIMULTANEOUSLY, AND NEW RUMBLER SIRENS THAT SEND OUT VIBRATING PULSINGS TO GET DRIVERS' ATTENTION. THIS GUY RIGHT IN FRONT OF YOU IS NOT MOVING. >> NO, HE CAN'T HEAR YOU. >> Reporter: BATTALION CHIEF MAURICIO SEGURA SEES IT EVERY DAY. IF YOU'RE DELAYED 15 SECONDS, 30 SECONDS, WHAT DOES THAT MEAN IN A MEDICAL EMERGENCY OR A FIRE? THEY COULD MEAN LIFE OR DEATH. >> Reporter: A CARDIAC ARREST VICTIM MAY HAVE JUST TEN MINUTES BEFORE BRAIN DAMAGE. A SMALL FIRE CAN GROW TO SOMETHING VERY BIG IN JUST 30 SECONDS. IN A BUSINESS WHERE EVERY SECOND COUNTS, FRONT-LINE RESPONDERS SAY JUST GETTING THERE IS TAKING LONGER. TOM COSTELLO, NBC NEWS, PARKER, COLORADO. >>> UP NEXT, ALLERGY SEASON IS HERE. WHY IT IS STARTING EARLIER, ENDING LATER, AND MAKING YOU STUFFIER. HOW YOU CAN FIGHT IT. >>> IF YOU SUFFER FROM SEASONAL ALLERGIES, YOU MAY HAVE NOTICED IT. THE PROBLEM IS GETTING WORSE, AND IT'S LASTING LONGER. ANNE THOMPSON EXPLAINS WHY IT'S HAPPENING, AND HOW YOU CAN BREATHE EASIER. >> Reporter: THESE DAYS, WHEN NICOLE LEVIN WEARS A MASK, IT'S FOR POLLEN, NOT COVID. >> MY ASTHMA HAS GOTTEN SO MUCH WORSE WITH THE POLLEN, AND IT'S STARTING EARLIER. >> Reporter: ALLERGY SEASON THAT USED TO BEGIN IN LATE MARCH NOW STRIKES HER IN FEBRUARY, FORCING THIS NEW YORK TEACHER TO DOUBLE HER ALLERGY MEDICINE, BUT IT'S NOT ENOUGH. >> FROM WORK I USED TO MISS ONE TO TWO DAYS DURING THE ALLERGY SEASON IF MY ASTHMA WAS FLARING. BUT NOW IT'S UP TO THREE TO FIVE DAYS. >> Reporter: THE SUFFERING IS NATIONWIDE. NEW GOVERNMENT RESEARCH SHOWS POLLEN SEASON STARTS 20 DAYS EARLIER AND LASTS 10 DAYS LONGER. DR. PURVI PARIKH IS AN ALLERGIST IN NEW YORK CITY. WE KNOW CLIMATE CHANGE IS MAKING THE ALLERGY SEASON LONGER. BUT IS IT ALSO AFFECTING THE POTENCY? >> ABSOLUTELY. WE'RE SEEING MUCH HIGHER COUNTS AND MUCH EARLIER ON. >> Reporter: THERE IS 21% MORE POLLEN IN THE AIR THAN IN 1990, FUELLED BY CARBON DIOXIDE FROM MAN-MADE CLIMATE CHANGE. >> AS THE CO2 LEVELS INCREASE, THE PLANTS ARE THRIVING EVEN MORE SO. AS A RESULT, THEY'RE PRODUCING MUCH HIGHER LEVELS OF POLLEN THAN USUAL. >> Reporter: LEADING TO MORE ALLERGIES, WHICH CAN LEAD TO MORE ASTHMA. ASTHMA CAUSES 11 DEATHS A DAY IN THE U.S. TO COMBAT ALLERGIES, DR. PARIKH RECOMMENDS 24-HOUR ANTIHISTAMINES INSTEAD OF DECONGESTANTS. OVER-THE-COUNTER NASAL SPRAYS AND EYE DROPS CAN HELP TOO. FOR NICOLE LEVIN, PREPARATION IS EVERYTHING. >> IF I DIDN'T HAVE A TREATMENT PLAN, I WOULDN'T BE ABLE TO FUNCTION. >> Reporter: TO SURVIVE A WORSENING ALLERGY SEASON ON A CHANGING PLANET. ANNE THOMPSON, NBC NEWS, NEW YORK. >>> AND NEXT, A PHOTOGRAPHER GETS TO PURSUE HIS PASSION THANKS TO THE STUDENTS WHO ENGINEERED A WAY TO HELP HIM. "INSPIRING AMERICA" IS >>> IF YOU LOOK AT THE SKY TONIGHT, YOU MIGHT SEE SOMETHING AMAZING. FIVE PLANETS, MERCURY, JIERPT JUPITER, VENUS URANUS AND MARS ALL ALIGNING NEAR THE MOON. NASA SCIENTISTS SAY THE BEST TIME TO SEE THE RARE PHENOMENON IS RIGHT AFTER SUNSET ALONG THE WESTERN HORIZON. THE LAST FIVE-PLANET ALIGNMENT WAS VISIBLE BACK IN JUNE. >>> AND FINALLY, THE STORY OF A PHOTOGRAPHER, A GROUP OF YOUNG ENGINEERS, AND THE TEAM-UP THAT'S INSPIRING AMERICA. HERE IS JESSE KIRSCH. >> Reporter: NO MATTER HOW MANY WORDS A PICTURE SAYS, IT MAY NOT REVEAL MUCH FROM THE OTHER SIDE OF THE CAMERA. BUT THESE IMAGES FROM THE PHOTOGRAPHER TELL QUITE THE STORY. WHAT DO YOU LOVE ABOUT PHOTOGRAPHY? >> I KNOW THAT IT TAKES -- IT TAKES YOU ON A JOURNEY, AND YOU DON'T HAVE TO GO VERY FAR. >> Reporter: STILL, AURELIAN BARBER'S JOURNEY HAS NOT BEEN SIMPLE. HE HAS LIMITED MUSCLES AND JOINS CONFINING HIM TO A WHEELCHAIR, MAKING IT DIFFICULT TO HOLD A CAMERA. >> I'M NOT ABLE TO OPEN MY HANDS AND GRASP OF IT. >> Reporter: USING A TIMER, EVEN BITING DOWN TO RECORD VIDEOS, THE 45-YEAR-OLD STILL FOUND A WAY TO OVERCOME HIS STRUGGLE. EVEN BEING ABLE TO LOOK AT A PHOTO AND KNOW YOU TOOK IT IS SPECIAL? >> YES. >> Reporter: BUT THE CLEVELAND MAN WANTED TO DO MORE, WHEN WORD WORD REACHED SOME ENGINEERING STUDENTS AT NEARBY CASE WESTERN UNIVERSITY. WITH HELP FROM BARBER AND AN ADVISER, IN THESE SPACES STUDENTS DESIGNED AND BUILT A MOTORIZED ARM FOR A SWIVELING GIMBEL, TAKING BARBER'S PHOTOGRAPHY TO NEW HEIGHTS. >> I DIDN'T WANT TO NOT FINISH IT OR GIVE UP ON IT BECAUSE I WANTED HIM TO HAVE SOMETHING HE COULD TAKE PHOTOGRAPHS WITH. >> WE WERE REALLY ABLE TO CHANGE SOMEBODY'S LIFE. THAT'S HUGELY GRATIFYING FOR US. >> Reporter: ONE PASSION SUPPORTING ANOTHER, HELPING THESE PICTURES SAY A LOT MORE. >> EVEN SOMEBODY WITH A PHYSICAL DISABILITY CAN HAVE DREAMS AND IDEAS, ARTISTIC IDEAS WHEN IT SHOULD NOT SLOW THEM DOWN. >> Reporter: JESSE KIRSCH, NBC NEWS, CLEVELAND. >>> THAT'S "NIGHTLY NEWS" FOR THIS TUESDAY. THANK YOU FOR WATCHING. I'M LESTER HOLT. PLEASE TAKE CARE OF YOURSELF AND EACH OTHER. GOOD NIGHT.