A fiery car crash sent Kyle Larson's car airborne and flying debris injured a number of fans Saturday in the waning moments of the NASCAR Nationwide Series season-opener.

The wreck, which occurred almost as Tony Stewart was taking the chequered flag for victory, appeared to begin when Regan Smith was turned sideways and took several competitors behind him in a pack.

Larson, making his first start in the NASCAR stock car second-tier series, then sailed into the catch-fencing.

Larson's car tore a hole in the fence, and his engine sheared off with at least one tire and other debris flying into the stands.

ESPN quoted Daytona Beach police as saying 15 fans were injured, one critically.

"Our prayers and thoughts are with everybody they are working on," NASCAR President Mike Helton said.

Emergency medical personnel immediately went into the stands to treat those hurt, but NASCAR officials could not immediately confirm the number and nature of the injuries. None of the drivers was injured.

"There was obviously some intrusion into the fence, and fortunately with the way the events are equipped, there was plenty of emergency workers ready to go," Helton told ESPN. "They all jumped on it pretty quickly.

"Right now, it's just a function of trying to determine what all damage is done," added Helton, who said some injured fans were being taken to local hospitals.

Another big crash, involving 11 cars, took place with five laps remaining, with driver Michael Annett taken to hospital after hitting a barrier.

"We've always known since racing started this is a dangerous sport," Stewart said. "As much as we want to celebrate, I'm more concerned about the fans and the drivers right now."