Four-time IndyCar Series champion Dario Franchitti fractured two vertebrae, broke his right ankle and sustained a concussion when his car went airborne into a catch fence during the final lap of the Grand Prix of Houston on Sunday, with flying debris injuring 13 spectators and a series official.
Franchitti was transported to a hospital where the three-time Indianapolis 500 winner would be held overnight, and a series official was treated for minor injuries.
Houston Fire Department spokesman Ruy Lozano said 11 of the 13 injured fans were treated on site at Reliant Park. Lozano said two were taken to the hospital for treatment.
The accident occurred when Franchitti's car clipped the tire of the car driven by Takuma Sato when the two were coming out of Turn 5 at the Reliant Park race course. After Franchitti's car hit the fence, it landed back on the track. Also involved in the wreckage was E.J. Viso, whose car collided with Sato's car.
The accident brought an immediate caution flag and the race was halted with Power declared the winner.
Sato said his car clipped the wall before Franchitti's car collided with his.
"On the last lap I caught the marbles and brushed the wall and lost momentum," Sato said. "A couple cars passed me as I was off line and in Turn 5. I got very loose and Dario and I came together. Hopefully Dario is OK."
The accident in Turn 5 was reminiscent of Dan Wheldon's fatal 2011 crash at Las Vegas; in both cases, competitors had to drive through the wreckage.
It was a sobering moment for race winner Will Power, who broke his back in the Las Vegas crash, and Scott Dixon, who took control of the IndyCar championship race Sunday but passed by teammate Franchitti's car and waved in an attempt to get an update on his condition.
"The smells and the visuals, for me, and even talking to Will, you have the remnants of Vegas popping into your head with you coming around the corner and you can't drive through it because there's a field of debris," Dixon said. "There was no near the amount of damage that we saw [in 2011], but seeing the replay was a big shock."
Dixon will head to Auto Club Speedway in Fontana for the series finale on Oct. 19 with a 25-point lead over Helio Castroneves, who surrendered first place in the standings when he finished 23rd after mechanical problems Sunday.
Wire service and Internet reports contributed to this story.