The Big One hit only 15 laps into the Daytona 500, triggered when Aric Almirola turned into pole-winner Alex Bowman and started a 16-car pileup.
Minutes later, the race was stopped by lightning and fans who had been socially distanced in the grandstands instead had to seek shelter in the crowded concourse. Heavy rain followed, shutting down "The Great American Race'' for what will be a lengthy delay.
Christopher Bell started the melee when he pushed Almirola too hard near the front of the field and forced the Stewart-Haas Racing driver to bobble as he tried to avoid a slide.