Several fans were injured Saturday as pieces of race cars flew into the main grandstand at Daytona International Speedway during a spectacular 12-car accident at the end of the Drive4COPD 300 Nationwide race.

An hour after the race, there had been no official confirmation of the number of those injured or of the severity of the injuries, but at least four fans were removed from the grandstands on stretchers.

According to a report by the Associated Press,

Volusia County spokesman Dave Byron said six people with serious injuries were taken by ambulance to Halifax Health Medical Center near the speedway.

"Those six met the condition of trauma patients," Byron said, adding one person was taken to Memorial Health in Ormond Beach, and one person was taken to Halifax in Port Orange. Those two were "not serious injuries."

The accident occurred as a large pack of drivers were racing for the win. The wreck began as second-place Brad Keselowski hit first-place Regan Smith as they maneuvered in the draft. Drivers tried to avoid their spinning cars, but 10 other cars became involved in the crash.

The Chevrolet of rookie driver Kyle Larson was hit and pushed into the air, and it hit the grandstand fence at one of the fence’s support posts. The entire front end of Larson’s car was sheared away, and the engine burst through the fence and landed on a spectator concourse. A tire from Larson’s car sailed high into the grandstand, and other parts also flew into the seating areas.

Several drivers involved in the crash were evaluated at the track’s infield medical center, but none was injured.

Tony Stewart, who won the race, said he saw the crash in his car’s rear-view mirror and said, ‘That's the worst image I've ever seen in a race in my life.”

The crash was similar to an April 2009 crash at Talladega Superspeedway at the finish of a Sprint Cup race. Brad Keselowski crashed into Carl Edwards’ car, sending it sailing into the grandstand fence. Pieces of Edwards’ car flew into the stands, injuring eight fans, one seriously.

Mike Hembree is NASCAR Editor for SPEED.com and has been covering motorsports for 31 years. He is a six-time winner of the National Motorsports Press Association Writer of the Year Award.