>>> TONIGHT, THE EMERGENCY IN CALIFORNIA AS THE STATE'S LARGEST WILDFIRE OF THE YEAR EXPLODES TO NEARLY 400,000 ACRES. THE NEW IMAGES OF THE PARK FIRE. IT'S NOW BIGGER THAN THE CITY OF LOS ANGELES AND THE SIXTH LARGEST IN THE STATE'S HISTORY. MORE THAN 100 HOMES AND BUILDINGS DESTROYED. THOUSANDS UNDER EVACUATION ORDERS. NOW THE SMOKE TRIGGERING AIR QUALITY ALERTS IN MULTIPLE OTHER STATES. >>> ALSO TONIGHT, 99 DAYS TO ELECTION DAY AND KAMALA HARRIS'S VEEPSTAKES HEATING UP. TWO OF THE TOP CONTENDERS CAMPAIGNING TOGETHER. IT COMES AS PRESIDENT BIDEN PROPOSES SWEEPING REFORMS TO THE SUPREME COURT. BUT CAN IT GO ANYWHERE IN CONGRESS? >>> FORMER PRESIDENT DONALD TRUMP AGREEING TO SIT WITH THE FBI FOR AN INTERVIEW ABOUT THE ATTEMPT ON HIS LIFE AS WE LEARN NEW DETAILS ABOUT THE SHOOTER. >>> THE HORROR IN THE UK. THE STABBING RAMPAGE AT A DANCE CLASS DURING A TAYLOR SWIFT-THEMED EVENT. TWO CHILDREN KILLED. NINE INJURED. AND THE TEEN IN CUSTODY TONIGHT. >>> PLUS, DAY THREE OF THE OLYMPIC COMPETITION HERE IN PARIS. THE U.S. MEN'S GYMNASTICS TEAM PULLING OFF SOMETHING IT HASN'T DONE IN 16 YEARS. AND WITH ALL EYES ON THE WOMEN'S TEAM AHEAD OF TOMORROW'S FINAL WE TALKED TO THEIR BIGGEST FANS, THEIR PARENTS. >>> AND THE AMERICAN WATER POLO STAR MAKING A SPLASH IN PARIS WITH SUPPORT FROM HER HUSBAND, WHO FACES THE FIGHT OF HIS LIFE. >> Announcer: THIS IS NBC "NIGHTLY NEWS." REPORTING TONIGHT FROM THE OLYMPICS IN PARIS. HERE IS LESTER HOLT. >>> GOOD EVENING AND WELCOME FROM PARIS. BEHIND ME THE ARC DE TRIOMPHE, AN ENDURING SYMBOL OF FRANCE AND THIS CITY, WHICH IS OUR HEADQUARTERS FOR THE NEXT TWO WEEKS. WE HAVE A LOT TO REPORT FROM THE OLYMPICS COMING UP, BUT WE WANT TO BEGIN WITH THE UNFOLDING FIRE DISASTER IN NORTHERN CALIFORNIA. ONE OFFICIALS HAVE LABELED THE PARK FIRE IS STILL TONIGHT DRIVING WIDESPREAD EVACUATIONS ACROSS AREAS THAT INCLUDE PARADISE. THAT'S A CITY DECIMATED BY FIRE IN 2018, LEAVING SCORES DEAD. AT MORE THAN 370,000 ACRES THE PARK FIRE, THE LARGEST FIRE BURNING NOW IN THE WEST, IS DEFYING EFFORTS TO CONTAIN IT AS IT RAPIDLY BECOMES ONE OF CALIFORNIA'S LARGEST WILDFIRES EVER. STEVE PATTERSON IS THERE AND TELLS US THERE IS A REASON WHY THESE FIRES ARE INTENSIFYING. >> Reporter: TONIGHT THE NATION'S LARGEST WILDFIRE BRAZEN AND BOUNDLESS. FIREFIGHTERS SPREAD THIN OVER THE PARK FIRE, A THREAT ZONE NOW SPRAWLING ACROSS FOUR COUNTIES. IN LESS THAN A WEEK GROWING INTO CALIFORNIA'S SIXTH LARGEST WILDFIRE EVER. ACCORDING TO CAL FIRE, THE BIGGEST IN STATE HISTORY ARE ALL FROM THE LAST SIX YEARS. AN ERA OF CLIMATE-DRIVEN FIRE SEASON THAT SCIENTISTS SAY STARTS SOONER AND LASTS LONGER. >> SEEMS TO BE JUST A CONTINUOUS CYCLE OF THESE. IT WEARS ON OUR COMMUNITY. >> Reporter: THOUSANDS UNDER EVACUATION ALERTS. DOZENS OF HOMES DESTROYED. ALONG WITH COUNTLESS OTHER CLOSE CALLS. >> I'M JUST VERY EMOTIONALLY DRAINED AND GRATEFUL. GRATEFUL THAT WE HAVE OUR HOUSE. >> Reporter: THE PARK FIRE IS JUST ONE OF 100 LARGE ACTIVE WILDFIRES BURNING ACROSS THE AMERICAN WEST AND CANADA. TODAY NEW EVACUATIONS IN COLORADO. ALL OF IT SENDING PLUMES OF SMOKE AS FAR EAST AS MINNEAPOLIS. IN CENTRAL CALIFORNIA ONE BLAZE LEVELING THIS HISTORIC MINING TOWN. BACK IN NORTHERN CALIFORNIA MUCH OF THE BURN ZONE COVERS AREAS REPEATEDLY IMPACTED BY FIRE INCLUDING THE 2018 CAMP FIRE THAT CLAIMED THE LIVES OF 85 PEOPLE IN PARADISE, CALIFORNIA. RICK PERRO LOST HIS HOME IN PARADISE AND THOUGHT THIS TIME HIS FAMILY WAS FINALLY SAFE. HIS CAT SURVIVED THE FIRST FIRE, ONLY TO PERISH HERE. >> SEEING THIS WAS HORRIBLE AGAIN. IT WAS SAD BECAUSE WE WEREN'T HERE. WE COULDN'T HELP HIM. >> Reporter: TWO HOMES, SIX YEARS, A LIFETIME OF MEMENTOS AND MEMORIES TURNED TO ASH. >> THE THIRD TIME IS THE CHARM. AND I'M NOT SURE EXACTLY WHAT THAT'S GOING TO LOOK LIKE. >> AND STEVE, THE ARSON SUSPECT BEHIND THIS PARK FIRE IS EXPECTED IN COURT. >> Reporter: AND LESTER, WE'VE REACHED OUT TO THAT SUSPECT, RONNIE STOUT II, IN FRONT OF A JUDGE THIS AFTERNOON. WE'LL LEARN WHAT CHARGES HE'S FACING LATER TODAY. MEANWHILE, IT'S EXPECTED TO GET A WHOLE LOT HOTTER ON THIS FIRE OVER THE NEXT FEW DAYS, FURTHER RAISING THE FIRE DANGER IN AN ALREADY DANGEROUS FIGHT. LESTER? >> ALL RIGHT, STEVE PATTERSON, THANK YOU. >>> TONIGHT, WITH LESS THAN 100 DAYS TO GO UNTIL THE ELECTION, VICE PRESIDENT HARRIS IS ZEROING IN ON HER BIG DECISION ON A RUNNING MATE. PLUS A CONTROVERSIAL NEW PLAN FROM THE PRESIDENT ABOUT THE SUPREME COURT. KELLY O'DONNELL WITH LATE DETAILS. >> Reporter: A 99-DAY SPRINT TO NOVEMBER 5th. PROMINENT DEMOCRATIC GOVERNORS AND POTENTIAL VP PICKS, PENNSYLVANIA'S JOSH SHAPIRO AND MICHIGAN'S GRETCHEN WHITMER, ON THE TRAIL FOR KAMALA HARRIS. >> LET'S WAKE UP IN NOVEMBER AND SAY THE WORDS "MADAM PRESIDENT." >> Reporter: THEIR MESSAGES PROVIDE A WINDOW INTO THE RUNNING MATE SEARCH. WITH ABOUT TEN DAYS LEFT FOR THE VICE PRESIDENT TO MAKE HER DECISION. >> KAMALA HARRIS'S NAME IS GOING TO BE ON THAT BALLOT. AND I FOR ONE AM GOING TO BE PUSHING THAT BUTTON FOR KAMALA HARRIS. I KNOW YOU WILL TOO. >> Reporter: HER TEAM CALLING FOR A WEEK OF ACTION. ON THE SUPREME COURT AND ABORTION RIGHTS. AS IOWA'S RESTRICTION ON ABORTION AFTER ABOUT SIX WEEKS GOES INTO EFFECT TODAY. HARRIS ON SOCIAL MEDIA TIED THE LAW TO FORMER PRESIDENT TRUMP. >> WHICH MAKES IOWA THE 22nd STATE IN OUR COUNTRY TO HAVE A TRUMP ABORTION BAN. >> Reporter: IN MINNESOTA SATURDAY FORMER PRESIDENT TRUMP CALLED OUT HARRIS ON IMMIGRATION. >> I WILL TERMINATE EVERY SINGLE OPEN BORDER POLICY OF THE BIDEN-HARRIS ADMINISTRATION. AND WE WILL SEAL THE BORDER -- >> Reporter: BOTH HARRIS AND PRESIDENT BIDEN SAY DRAMATIC CHANGE IS NEEDED AT THE SUPREME COURT. >> WE NEED THESE REFORMS TO RESTORE TRUST IN THE COURTS. >> Reporter: THE PRESIDENT CALLING FOR A CONSTITUTIONAL AMENDMENT TO HOLD PRESIDENTS ACCOUNTABLE FOR CRIMES COMMITTED IN OFFICE AFTER MR. TRUMP'S WIN ON IMMUNITY. TERM LIMITS TO CAP JUSTICES AT 18 YEARS ON THE COURT. A BINDING CODE OF ETHICS. >> THE SUPREME COURT'S CURRENT ETHICS CODE IS WEAK AND, EVEN MORE FRIGHTENING, VOLUNTARY. >> Reporter: GETTING NECESSARY CONGRESSIONAL APPROVAL WOULD BE HARD. >> PRESIDENT BIDEN AND HIS LEFTIST ALLIES DON'T LIKE THE CURRENT COMPOSITION OF THE COURT, SO THEY WANT TO SHRED THE CONSTITUTION TO CHANGE IT. >> MEANWHILE, KELLY, THERE ARE SOME NEW DEVELOPMENTS IN THE INVESTIGATION INTO THE ASSASSINATION ATTEMPT AGAINST FORMER PRESIDENT TRUMP. >> Reporter: THAT'S RIGHT. CONGRESS ANNOUNCED A NEW BIPARTISAN TASK FORCE TO INVESTIGATE THE ASSASSINATION ATTEMPT. TODAY THE FBI SAYS IT HAS STILL NOT DETERMINED MOTIVE BUT HAS EVIDENCE OF COMPLEX PLANNING BY THE GUNMAN. THE BUREAU'S DONE MORE THAN 450 INTERVIEWS AND SAYS FORMER PRESIDENT TRUMP AGREED TO PARTICIPATE IN WHAT THEY CALL A VICTIM INTERVIEW. LESTER? >> KELLY O'DONNELL TONIGHT, THANK YOU. >>> IN NORTHERN ENGLAND TODAY A HORRIFYING ATTACK AT A SCHOOL EVENT. POLICE SAY A TEEN WITH A KNIFE WENT ON A STABBING RAMPAGE, KILLING TWO CHILDREN, INJURING NINE OTHERS, AND WOUNDING TWO ADULTS. RICHARD ENGEL HAS LATE DETAILS. >> Reporter: WHEN PARENTS WORRY ABOUT A SENSELESS ATTACK, THIS IS WHAT THEY FEAR. AROUND NOON TODAY IN SOUTHPORT IN NORTHERN ENGLAND NEAR LIVERPOOL AN ASSAILANT WALKED INTO A DANCE AND YOGA STUDIO AND BEGAN STABBING CHILDREN. IT WAS DURING A SOLD-OUT TAYLOR SWIFT-THEMED CLASS FOR 6 TO 11-YEAR-OLDS. WITNESSES SAW BLOODIED CHILDREN BEING TAKEN OUT. ONE DESCRIBING IT LIKE A HORROR MOVIE. >> TWO CHILDREN HAVE DIED AS A RESULT OF THE INJURIES SUSTAINED IN THIS MORNING'S KNIFE ATTACK. NINE OTHER CHILDREN HAVE BEEN INJURED. AND SIX OF THEM ARE IN A CRITICAL CONDITION. >> Reporter: THE SUSPECT WAS ONLY IDENTIFIED BY POLICE AS A 17-YEAR-OLD MALE FROM A NEARBY TOWN. >> I'M STILL SHAKING. I STILL CAN'T JUST -- I CAN'T THINK WHAT IS HAPPENING BECAUSE I THINK IT'S SHOCKING EVERYONE. >> Reporter: NO MOTIVE WAS GIVEN. IT'S NOT BEING INVESTIGATED AS TERRORISM. NO OTHER SUSPECTS ARE BEING SOUGHT. >> OUR THOUGHTS AND CONDOLENCES WITH THE VICTIMS, THEIR FAMILIES, THEIR FRIENDS AND THE WIDER COMMUNITY. IT'S ALMOST IMPOSSIBLE TO IMAGINE THE GRIEF THAT THEY'RE GOING THROUGH AND THE TRAUMA THAT THEY'RE GOING THROUGH. >> Reporter: KING CHARLES TONIGHT SAID IN A STATEMENT, "MY WIFE AND I HAVE BEEN PROFOUNDLY SHOCKED TO HEAR OF THE UTTERLY HORRIFIC INCIDENT." LESTER? >> ALL RIGHT, RICHARD, THANK YOU. >>> THE MIDEAST ON EDGE TONIGHT AS ISRAEL VOWS A MAJOR RESPONSE FOLLOWING A DEADLY ROCKET ATTACK ON DRUZE CHILDREN AT A PLAYGROUND. RAF SANCHEZ HAS LATE DETAILS. >> Reporter: TONIGHT ISRAELI PRIME MINISTER BENJAMIN NETANYAHU AT THE SOCCER FIELD WHERE 12 CHILDREN WERE KILLED IN A ROCKET BLAST SATURDAY. ISRAEL AND THE U.S. SAY THE STRIKE WAS CARRIED OUT BY IRANIAN-BACKED HEZBOLLAH FROM LEBANON, WHICH DENIES RESPONSIBILITY. ISRAEL SAYS IT'S THE WORST ASSAULT ON ITS CIVILIANS SINCE THE HAMAS TERROR ATTACK OF OCTOBER 7th. "OUR RESPONSE WILL COME, AND IT WILL BE SEVERE," NETANYAHU SAYS. THAT'S RAISING FEARS OF AN ALL-OUT WAR. WHILE IN THE MOUNTAIN VILLAGE OF MAJDAL SHAMS AND THE ISRAELI-CONTROLLED GOLAN HEIGHTS ANGUISH OVER SO MANY YOUNG LIVES LOST. THIS WAS A NORMAL SATURDAY NIGHT. IT WAS A LITTLE AFTER 6:00 P.M. KIDS PLAYING ON THIS SOCCER FIELD WHEN THE SIRENS STARTED BLARING AND JUST SECONDS LATER THAT ROCKET CAME CRASHING DOWN RIGHT HERE, BRINGING DEATH AND DESTRUCTION TO THIS COMMUNITY. AMONG THE DEAD, 13-YEAR-OLD JOHN IBRAHIM. WE MET HIS COUSIN, NIA. >> ALL OF MY FAMILY IS FEELING BAD AND CRYING. >> Reporter: BUT THERE'S ALSO ANGER. THIS CROWD CALLING NETANYAHU A KILLER, SAYING HE SHOULD HAVE DONE MORE TO KEEP THEIR CHILDREN SAFE. AND THE WHITE HOUSE SAYING TONIGHT PREDICTIONS OF ALL-OUT WAR BETWEEN ISRAEL AND HEZBOLLAH ARE, QUOTE, EXAGGERATED. LESTER? >> ALL RIGHT, RAF, THANK YOU. >>> LET'S TURN NOW TO THE PARIS OLYMPICS. THE U.S. MEN'S GYMNASTICS TEAM WINNING THEIR FIRST TEAM MEDAL IN 16 YEARS. AND THE U.S. WOMEN'S BASKETBALL TEAM OFF TO A DOMINANT START. TOM LLAMAS IS WITH US. TOM, A BIG DAY FOR AMERICANS. >> YEAH, LESTER, I WAS THERE AT GYMNASTICS, AND THAT ARENA WAS SO ELECTRIC. IT WAS UNCLEAR IF TEAM USA WOULD MEDAL. AND THEN IN THE SECOND ROTATION SOMETHING HAPPENED. IT ALL CLICKED. EACH OF THEM WERE IN THE ZONE, CONTRIBUTING IN A MAJOR WAY. THEY DELIVERED ON ELECTRIFYING ROUTINE AFTER ROUTINE. >> FANS HERE AT BERCY ARENA CHEERING ON TEAM USA. THEY PROMISED REDEMPTION, AND THEY DELIVERED. >> IMPORTANT PASSAGE TO GET THROUGH. >> Reporter: STEPHEN NEDOROSCIK'S CLUTCH PERFORMANCE ON THE POMMEL HORSE CLINCHING THE BRONZE FOR THE AMERICAN MEN. >> DISMOUNT. THAT'S IT! >> HOW DOES IT FEEL? >> UNBELIEVABLE. >> UNREAL. >> WENT UP THERE, DID MY JOB, AND AS SOON AS I LANDED I WAS LIKE I THINK WE MIGHT HAVE DID THAT, BABY. >> Reporter: THE 16-YEAR MEDAL DROUGHT FOR THE MEN OF TEAM USA NOW OFFICIALLY OVER. >> I THINK ABOUT ALL THE PEOPLE BEHIND ME. I KNEW I HAD THE WHOLE U.S. BEHIND ME. >> Reporter: REDEMPTION ALSO IN THE AIR AT SKATEBOARDING. >> THIS IS WHAT CAN BE THE DIFFERENCE MAKER. >> Reporter: WHERE NYJAH HUSTON WON BRONZE AFTER MISSING THE PODIUM IN TOKYO. HIS TEAMMATE JAGGER EATON WON SILVER, WITH THIS MONSTER TRICK. >> HE CAN'T BELIEVE HE LANDED IT. WE CAN'T BELIEVE HE LANDED IT. >> WE HAD TO BRING IT. IN L.A. YOU BET WE'RE GOING TO BRING IT AGAIN. >> Reporter: OVER AT THE POOL THE U.S. PICKING UP FOUR MORE MEDALS TONIGHT. RYAN MURPHY WON BRONZE, THEN FOUND OUT THE GENDER OF HIS BABY ON THE WAY IN A SIGN HELD UP BY HIS WIFE. >> THE UNITED STATES CONTROL IT. >> Reporter: WHILE TEAM USA WOMEN'S BASKETBALL MADE THEIR PARIS DEBUT, EASILY PUTTING AWAY JAPAN. THEIR 56th STRAIGHT WIN AT THE OLYMPICS. THE LAST TIME THEY LOST? 1992. AND A BLOCKBUSTER MATCH UP AT ROLAND-GARROS, NOVAK DJOKOVIC KNOCKING OUT RAFAEL NADAL IN SINGLES. IT COULD BE THE LAST TIME THE TWO TENNIS GIANTS PLAY EACH OTHER AT A MAJOR TOURNAMENT. >> THIS OUGHT TO BE SWEET. >> Reporter: BUT THE BEST CELEBRATION OF THE DAY HAS TO GO TO AMERICAN FENCER NICK ITKIN. >> THIS IS WHY WE LOVE FENCING EVEN WHEN WE'RE NOT SURE EXACTLY WHAT'S GOING ON. >> Reporter: TOM LLAMAS, NBC NEWS, PARIS. >> AND YOU CAN WATCH ALL OF THE COVERAGE OF THE OLYMPICS AT 8:00 P.M. EASTERN TONIGHT. RYAN MURPHY AND LILLY KING LEAD TEAM USA IN SWIMMING. PLUS IT'S THE DRAMATIC CONCLUSION OF THE MEN'S GYMNASTICS TEAM EVENT. >>> IN 60 SECONDS, THEY WERE KEY TO THE OUTCOME IN 2020. HOW DO BLACK MEN SEE THE RAPIDLY CHANGING PRESIDENTIAL RACE NOW? TURNS OUT IT'S >>> BACK WITH THE RACE FOR THE WHITE HOUSE AND A CRITICAL BLOC OF VOTERS WHO COULD MAKE ALL THE DIFFERENCE. YAMICHE ALCINDOR IS IN GEORGIA TALKING WITH BLACK MEN ABOUT HOW THE SHAKE-UP IN THE RACE IMPACTS THEIR VOTE. >> Reporter: IN BATTLEGROUND GEORGIA BLACK MEN VOTERS WILL BE CRITICAL IN THE RACE TO THE WHITE HOUSE. >> I LIKE RFK. >> Reporter: JUSTIN SAMUELS AND DORIAN GRIFFIN ARE BOTH 32-YEAR-OLD SMALL BUSINESS OWNERS. SAMUELS IS AN INDEPENDENT. >> HOW HAS VICE PRESIDENT HARRIS BEING THE TOP OF THE TICKET IMPACTED THE WAY THAT YOU SEE THIS ELECTION? >> HER BEING THE TOP OF THE TICKET REALLY MADE ME THINK ABOUT CREATING ANOTHER HISTORIC MOMENT, NOT JUST FOR THE COUNTRY BUT FOR ALSO THE BLACK COMMUNITY AS A WHOLE TOO. I THINK THERE'S A LOT THAT SHE HAS TO PROVE. THERE ARE A LOT OF YOUNG MEN IN THIS COUNTRY WHO NEED TO BE OKAY WITH A WOMAN LEADING THE COUNTRY. >> Reporter: GRIFFIN IS A REPUBLICAN. HE SAYS HE'S STILL VOTING FOR TRUMP. >> AND TELL ME WHAT APPEALS TO YOU ABOUT TRUMP. >> HIS BUSINESS ACUMEN. WHEN DONALD TRUMP WAS PRESIDENT, WE WERE ALL DOING A LOT BETTER FINANCIALLY. HE'S ALWAYS BEEN A BUSINESS ICON. SO WHY WOULDN'T WE WANT THAT BUSINESS ICON TO BE PRESIDENT? >> Reporter: AND HE HAS THIS TO SAY ABOUT HARRIS. >> I THINK SHE HASN'T DONE ANYTHING WORTH MENTIONING. >> Reporter: WHAT WOULD YOU HAVE WANTED TO SEE VICE PRESIDENT HARRIS ACCOMPLISH THAT SHE HAS NOT? >> I WOULD HAVE LIKED HER TO KIND OF BRING A CALM TO THE BORDER. THE BORDER CRISIS HAS GOTTEN OUT OF HAND. >> Reporter: IN 2020 PRESIDENT BIDEN NARROWLY FLIPPED GEORGIA BLUE, WINNING BY JUST UNDER 12,000 VOTES. DEMOCRAT DARUS ROLLINS SAYS HE'S EXCITED FOR HARRIS. >> I'VE NEVER SEEN ENTHUSIASM LIKE THIS THIS FAST. >> AND YOU HAVE CONCERNS ABOUT VICE PRESIDENT HARRIS'S BACKGROUND AS A PROSECUTOR. WHAT GOT YOU OVER THEM? >> WHEN I STARTED DOING THE RESEARCH, WHEN YOU SEE THOSE TYPE OF THINGS THAT AREN'T OFTEN TALKED ABOUT, THAT RESONATES WITH ME. >> Reporter: AND NOW ALL THREE MEN ARE WAITING FOR NOVEMBER'S ELECTION RESULTS. YAMICHE ALCINDOR, NBC NEWS, ATLANTA. >>> STILL AHEAD, IF YOU THINK IT'S TOUGH BEING A TO ♪♪ >>> SOME OF THE HARDEST MOMENTS IN THESE OLYMPICS ARE NOT ON THE FIELD OF PLAY BUT RATHER IN THE STANDS. TONIGHT MY CONVERSATIONS WITH PARENTS OF TEAM USA'S GYMNASTS ABOUT WHAT IT'S LIKE. >> HENRY, YOUR LITTLE GIRL IS AN OLYMPIAN. WHAT IS THAT LIKE? >> WOW. SO EXCITING, MAN. NOBODY COULD EVER TAKE THAT AWAY FROM HER. >> Reporter: HENRY RIVERA IS THE FATHER OF HEZLY RIVERA. >> NOBODY'S HAD A BETTER TIME TONIGHT IN THE STANDS THAN HER PARENTS. >> Reporter: AT 16 THE YOUNGEST MEMBER OF THE USA WOMEN'S GYMNASTICS TEAM. THIS VIRAL VIDEO OF HER DAD BARELY ABLE TO LOOK DURING HER ROUTINE AT THE WORLD CHAMPIONSHIPS REMINDING THE PRESSURE OF THESE MOMENTS CAN BE A SHARED EXPERIENCE. >> I USUALLY GET OUT OF THE ARENA AND JUST PACE MYSELF, PRAYING. THAT WAS JUST NERVES. YOU KNOW, MY LITTLE DAUGHTER'S THERE. >> Reporter: AND WHETHER YOUR DAUGHTER IS 16 OR 27 LIKE, SAY, SIMONE BILES. >> HOW STRESSFUL IS IT WATCHING HER AND DOES IT GET EASIER OVER TIME? >> IT DOES NOT. NOT FOR ME. >> Reporter: NIGHTS LIKE LAST NIGHT REINFORCING THAT FOR RONNIE AND NELLY BILES AFTER SIMONE BRIEFLY APPEARED TO BE IN PAIN DURING THE QUALIFYING SESSIONS. >> I SAID WHAT IS SHE DOING? IS SHE HURT? >> PLEASE DON'T LET HER BE HURT. >> Reporter: THEY ARE KIDS WHEN THEY START CHASING THIS DREAM TO FLY ABOVE THE REST. BUT SIMONE BILES, THE SENIOR MEMBER OF THE USA TEAM, STILL TAKES ASSURANCE FROM MOM AND DAD'S PRESENCE, JUST LIKE SHE ALWAYS HAS. >> DOES SIMONE FEEL BETTER HAVING YOU GUYS IN THE STANDS AND KNOWING YOU'RE RIGHT THERE? >> SHE DEFINITELY DOES. SHE KNOWS WHERE WE'RE SITTING, AND THAT'S THE MAIN THING FOR HER. >> Reporter: AND THEY PLAN TO BE RIGHT THERE ON TUESDAY WHEN SIMONE WRITES HER COMEBACK STORY IN PARIS. >> YOU HAVE SO MANY REASONS TO BE PROUD OF SIMONE. DO YOU THINK BACK TO THOSE DAYS WHEN YOU WERE WATCHING HER AS A KID? >> I NEVER THOUGHT THAT THIS WOULD BE WHAT I WOULD BE EXPERIENCING. AND NOT ONLY HAVE WE END UP WITH ONE OLYMPICS, THIS IS HER THIRD. THIS IS INCREDIBLE. >> AND REGARDING SIMONE BILES AND HER LEG, HER MOM TELLS ME SHE IS FINE AND THAT THE DOCTOR TOLD THEM THERE IS REALLY NOTHING FOR THEM TO WORRY ABOUT. >>> COMING UP, SHE DOMINATES THE POOL AND WATER POLO. HE SWAM THE ENGLISH CHANNEL. NEXT, HOW THEIR >>> THE U.S. WOMEN'S WATER POLO TEAM IS CHASING ITS FOURTH STRAIGHT GOLD MEDAL HERE IN PARIS, AND ONE TEAMMATE IS FINDING INSPIRATION IN HER HUSBAND, WHO'S FACING A TOUGH FIGHT OF HIS OWN. MORGAN CHESKY NOW WITH THEIR OLYMPIC LOVE STORY. >> Reporter: AMID THE CONTROLLED CHAOS OF AN OLYMPIC WATER POLO WORKOUT YOU'LL FIND MADDIE MUSSELMAN, COOL, CALM, AND CLUTCH. >> I JUST LOVE IT. I MEAN, I LOVE PLAYING. I JUST SHOW UP EVERY DAY JUST LIKE THANKFUL THAT I GET TO PLAY THIS SPORT. >> Reporter: THE 26-YEAR-OLD A CRUCIAL PART OF THE USA WOMEN'S TEAM THAT'S GOING FOR A RECORD FOURTH GOLD MEDAL IN PARIS. >> SHE'S ONE OF THE VERY FEW PEOPLE WHO LIVES HER VALUES LITERALLY EVERY DAY. >> Reporter: VALUES TESTED MORE THAN ANY MATCH THIS PAST FALL WHEN MADDIE AND HER HUSBAND PAT GOT A PHONE CALL FOLLOWING A CT SCAN FOR PAT'S NAGGING COUGH. >> THEY LET US KNOW IT WAS CANCER. IT'S A VERY RARE, AGGRESSIVE CANCER. ONLY LIKE 200 PEOPLE A YEAR GET IT. >> Reporter: DOCTORS CALLED IT NOT CARCINOMA, SHARING IT SPREAD FROM PAT'S LUNGS TO HIS BONES. HE JUST SWAM ACROSS THE ENGLISH CHANNEL FOR HIS 30th BIRTHDAY. NOW THE COUPLE THAT BONDED OVER A SHARED FAITH AND WATER POLO WERE TOLD THE CANCER WAS STAGE 4. >> WHEN WE FIRST FOUND OUT, I DIDN'T KNOW IF I WANTED TO COME BACK AND PLAY. JUST I -- OBVIOUSLY LIKE HE'S MY PRIORITY, WHAT WE'RE DOING, YOU KNOW, LIVING YOUR LIFE AND HAVE A CHALLENGE LIKE THIS, LIKE WATER POLO SEEMS REALLY SMALL. >> Reporter: THE TWO DECIDED TO MOVE THEIR WEDDING UP THAT WEEK. THEN TACKLED TREATMENT WITH OLYMPIC DEDICATION. MADDIE SUPPORTING PAT THROUGH INTENSE CHEMO BEFORE HEADING TO TEAM WORKOUTS. >> THEY'RE THESE HUMANS THAT TOOK ON THIS HUGE THING AND THEY'VE DONE IT WITH GRACE, AND IT'S BEEN AMAZING TO WATCH THEM. >> YOU'RE THERE IN A GRUELING PRACTICE, YOU KNOW, YOUR BODY IS HURTING, AND YOU THINK OF PAT. >> YEAH. AND I TELL MYSELF I CAN DO IT. >> Reporter: DREAMS OF GOING TO PARIS FUELING THEM BOTH. >> YOU THINK ABOUT THAT WHENEVER YOU'RE GETTING TREATMENTS, WHENEVER YOU'RE HAVING A ROUGH DAY? >> MM-HMM. YEAH. >> Reporter: NOW ALMOST A YEAR LATER THEY'RE AT THE OLYMPICS AND PAT'S TREATMENTS ARE FINALLY OFFERING HOPE. >> AND TO KNOW THAT YOU HAVE A GOLD MEDALIST WHO HAS YOUR BACK NO MATTER WHAT. >> IT'S PRETTY SPECIAL. >> TOUGH TO BEAT. >> TOUGH TO BEAT. I'M CERTAINLY -- I FEEL THE LUCKIEST MAN ALIVE. SO. YEAH. >> Reporter: TWO FIGHTERS INSPIRING EACH OTHER EVERY STEP OF THE WAY. MORGAN CHESKY, NBC NEWS, LONG BEACH, CALIFORNIA. >> AND THAT IS "NIGHTLY NEWS" FOR THIS MONDAY. THANK YOU FOR WATCHING. I'M LESTER HOLT. PLEASE TAKE CARE OF YOURSELF AND EACH OTHER. GOOD NIGHT.