Updated at 9:35 p.m. ET
DAYTONA BEACH, Fla. At least 33 fans were injured Saturday during a NASCAR race when a car flew into the fence at Daytona International Speedway, hurling a tire and large pieces of debris into the stands.
The accident happened on the last lap of the second-tier Nationwide Series race on the eve of Sunday's Daytona 500, which officials said would go on as scheduled.
The crash began as the field approached the checkered flag and leader Regan Smith attempted to block Brad Keselowski to preserve the win. That triggered a chain reaction, and rookie Kyle Larson hit the cars in front of him and went airborne into the fence.
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."
Daytona International Speedway released a statement from speedway President Joie Chitwood Saturday evening saying 28 people were injured in the accident in the race held the day before the season-opening Daytona 500.
According to the statement, emergency medical personnel transported 14 people off the property and 14 others were treated at the on-track care center.
"We are in the process of repairing the facility, and we will be ready to go racing tomorrow," Chitwood said.
Nathan Kimpel, 24, who works at a concession stand near where the crash happened, told CBS News correspondent Adriana Diaz that he saw 10 to 15 fans being carried out on stretchers.
"As soon as I saw the accident I just turned my head because I didn't want to get injured or anything," Kimpel told Diaz. "I saw the fence separate and more pieces of car parts flying up."
Meghan Willams, 20, who also works at a concession stand, told Diaz the crash sounded like an "earthquake." She saw people running and crying and a girl completely covered in engine oil.
Byron Cogdell, a spokesman for Halifax Health Medical Center, told CBS News that one of the 11 patents taken to the hospital was in critical condition and five more were listed as "trauma" patients.
Lindsay Rew, a spokeswoman for Florida Hospital Memorial Medical Center, said its Daytona Beach hospital had one fan there who was in good condition. She said they were expecting three more people who were coming by ambulance, but she didn't yet know their conditions.
"There obviously was some intrusion into the fence and fortunately with the way the event's equipped up, there were plenty of emergency workers ready to go and they all jumped in on it pretty quickly," NASCAR President Mike Helton said. "Right now, it's just a function of determining what all damage is done. They're moving folks, as we've seen, to care centers and take some folks over to Halifax Medical."
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 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 stands. 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."
"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."