The incident started when Kyle Busch tried to block Stewart's move to the outside on the final turn of the last lap. Busch's rear bumper hit Stewart's front end, causing Busch to spin around and slam hard into the wall.
Several other cars crashed but no serious injuries were reported.
"I don't like winning like that ... but I did what I had to do," Stewart said in a post-race interview after his second victory this season. "That's not the way you want to win these things. You feel bad because you want him to have a good day too."
The incident caused Busch to finish 14th, while Jimmie Johnson, Denny Hamlin, Carl Edwards and Kurt Busch claimed the second through fifth spots.
Kyle Busch left the track without commenting.
Copyright 2009 by United Press International.