The entire front end was sheared off Larson's car, and his burning engine wedged through a gaping hole in the fence. Chunks of debris from the car were thrown into the stands, including a tire that cleared the top of the fence and landed midway up the spectator section closest to the track.
The 20-year-old Larson stood in shock several yards away from his car as fans in the stands waived frantically for help. Smoke from the burning engine briefly clouded the area, and emergency vehicles descended on the scene.
Ambulance sirens could be heard wailing behind the grandstands at a time the race winner would typically be doing celebratory burnouts.
"It was freaky. When I looked to my right, the accident happened," said Rick Harpster of Orange Park, Fla., who had a bird's-eye view of the wreck. "I looked over and I saw a tire fly straight over the fence into the stands, but after that I didn't see anything else That was the worst thing I have seen, seeing that tire fly into the stands. I knew it was going to be severe."
Shannan Devine, of Egg Harbor Township, N.J., was sitting about 250 feet away from where the car smashed into the fence and could see plumes of smoke directly in front of her.
"I didn't know if there was a car on top of people. I didn't know what to think. I'm an emotional person and I immediately started to cry. It was very scary. Absolutely scary. I love the speed of the sport. But it's so dangerous," said Devine who was planning to attend her second Daytona 500.
She said many fans got in the way of rescue efforts by trying to take pictures and videos, even jumping over fencing in hopes of getting closer to the scene.
Shannon Speedway President Joie Chitwood said 14 fans were treated on site, and 14 others were taken to hospitals. Chitwood didn't give any updates on their conditions. Local officials said 19 fans were taken to neighboring hospitals, including two who were in critical condition but were later upgraded to stable.
The accident happened the day before the Sprint Cup Series season-opening Daytona 500 NASCAR's version of the Super Bowl. Daytona workers could be seen repairing the large section of fence where Larson hit, as well as the wall that was damaged in the accident.
"First and foremost our thoughts and prayers are with our race fans," Chitwood said. "Following the incident we responded appropriately according to our safety protocols, and had emergency medical personnel at the incident immediately.
"We're in the process of repairing the facility and will be ready to go racing tomorrow."
As emergency workers tended to injured fans and ambulance sirens wailed in the background, a somber Tony Stewart skipped the traditional post-race victory celebration.
Stewart, who won for the 19th time at Daytona and seventh time in the last nine season-opening Nationwide races, was in no mood to celebrate.
"The important thing is what is going on on the frontstretch right now," said Stewart, the three-time NASCAR champion. "We've always known, and since racing started, this is a dangerous sport. But it's hard. We assume that risk, but it's hard when the fans get caught up in it.
"So as much as we want to celebrate right now and as much as this is a big deal to us, I'm more worried about the drivers and the fans that are in the stands right now because that was ... I could see it all in my mirror, and it didn't look good from where I was at."
The accident spread into the upper deck and emergency crews treated fans on both levels. There were five stretchers that appeared to be carrying fans out, and a helicopter flew overhead. A forklift was used to pluck Larson's engine out of the fence.
"It's a violent wreck. Just seeing the carnage on the racetrack, it's truly unbelievable," driver Justin Allgaier said.
It was a chaotic finish to a race that was stopped for nearly 20 minutes five laps from the finish by a 13-car accident that sent driver Michael Annett to a hospital, where his Richard Petty Motorsports team said he would be held overnight with bruising to his chest.
The race resumed with three laps to go, and the final accident occurred with Smith trying to hold off Keselowski through the final turn.
"I tried to throw a block. It's Daytona, you want to go for the win here," Smith said. "I don't know how you can play it any different other than concede second place, and I wasn't willing to do that today. Our job is to put them in position to win, and it was, and it didn't work out."
As the cars began wrecking all around Smith and Keselowski, Stewart slid through for the win, but Larson plowed into Keselowski and his car was sent airborne into the fence. When Larson's car came to a stop, it was missing its entire front end. The 20-year-old, who made his Daytona debut this week, stood apparently stunned, hands on his hips, several feet away from his car, before finally making the mandatory trip to the care center.
He said his first thought was with the fans.
"I hope all the fans are OK and all the drivers are all right," Larson said. "I took a couple big hits there and saw my engine was gone. Just hope everybody's all right."
He said he was along for the ride in the last-lap accident.
"I was getting pushed from behind, I felt like, and by the time my spotter said lift or go low, it was too late," Larson said. "I was in the wreck and then felt like it was slowing down and I looked like I could see the ground. Had some flames come in the cockpit, but luckily I was all right and could get out of the car quick."
It appeared fans were lined right along the fence when Larson's car sailed up and into it, but Chitwood indicated there was a buffer. He said there would be no changes to the seating before the Daytona 500.
"We don't anticipate moving any of our fans," Chitwood said. "We had our safety protocols in place. Our security maintained a buffer that separates the fans from the fencing area. With the fencing being prepared tonight to our safety protocols, we expect to go racing tomorrow with no changes."
Larson's car appeared to hit where the cross-over gate a section that can be opened for people to travel back and forth from the infield to the grandstands is located in the fence. Previous accidents in which drivers hit crossover gates were severe, but the gates were in the wall and not the fence for Mike Harmon's accident at Bristol in 2002 and Michael Waltrip's at the same track in 1990.
Still, NASCAR senior vice president Steve O'Donnell said it would be studied.
"I think we look at this after every incident," O'Donnell said. "We've learned in the past certain protocols put in place today are a result of prior incidents. Again, our initial evaluation is still ongoing. But it's certainly something we'll look at. If we can improve upon it, we'll certainly put that in play as soon as we can."
Larson had been scheduled to race his sprint car later Saturday night in Ocala, Fla., and even seemed restless to get there during the late stages of the Nationwide race. He pulled out of the event following the accident.
"Honestly, the race itself pales in comparison to the injuries sustained by the fans," said Chip Ganassi, the team owner who has Larson in his driver development program. "Our thoughts and prayers go out to all the fans that were injured as a result of the crash. As for Kyle, I am very happy that he is OK."
Keselowski watched a replay of the final accident, and said his first thoughts were with the fans. As for the accident, he agreed he tried to make a winning move and Smith tried to block.
"He felt like that's what he had to do, and that's his right. The chaos comes with it," Keselowski said. "I made the move and he blocked it, and the two of us got together and started the chain events that caused that wreck. First and foremost, just want to make sure everyone in the stands is OK and we're thinking about them."
Keselowski said the incident could cast a pall on the Daytona 500.
"I think until we know exactly the statuses of everyone involved, it's hard to lock yourself into the 500," Keselowski said. "Hopefully, we'll know soon and hopefully everyone's OK. And if that's the case, we'll staring focusing on Sunday."
1. Tony Stewart
2. Sam Hornish Jr.
3. Alex Bowman
4. Dale Earnhardt Jr.
5. Parker Kligerman
6. Brian Scott
7. Justin Allgaier
8. Eric McClure
9. Robert Richardson Jr.
10. Travis Pastrana
O Daytona 500 • Sunday, 10 a.m., Ch. 13