A last-lap crash in Saturday's NASCAR Nationwide Series race at Daytona International Speedway has caused injuries among the crowd after the front end of one of the cars was torn off and pierced the debris fencing.
NASCAR has confirmed that 28 fans were injured in total, with 14 treated on site and a further 14 transferred to local hospitals.
Two of the injured people were reported to be in a critical condition, before being upgraded to 'stable'.
In the race to the finish line in the 300-mile event, reigning Sprint Cup champion Brad Keselowski and Regan Smith clashed at the front.
This triggered a multi-car pile-up behind in which series debutant Kyle Larson's car took off and struck the catch fencing, ripping away the entire front end of his car.
The fencing was unable to contain the debris, and a section of it was penetrated in the violent impact.
Although the engine and one wheel from Larson's car stayed close to the edge of the spectator area, the other wheel flew into the grandstand and landed among the seating.
"I'm not sure what ended up where," Larson said. "I took a couple of big hits and I saw my engine was gone."
All 12 drivers involved in the crash were uninjured, and released from the medical centre.
Tony Stewart won the race but chose not to celebrate amid concern for those involved in the accident.
"We've always known since racing was started this was a dangerous sport, but we assume that risk, and it's hard when the fans get caught up in it," said Stewart.
"So as much as we want to celebrate now and as much as this is a big deal to us, I'm more worried about the drivers and the fans in the stands right now, because I could see it all in the mirror, and it didn't look good from where I was."