Takuma Sato of A.J. Foyt Racing got them to wave the yellow flag after he hit the wall. Without too many people around him, he either ran into some marbles or caught some dirty air. Either way, he got loose and just veered over to the wall, smacked it, and steered safely down the straightaway. He managed to make it back to the pit, and they're looking at his car.
This was a lucky break for Helio Castroneves in the #3 Pennzoil car, because he had sustained some damage to the left rear wing after some minor contact. He was able to pit during Sato's yellow, get the rear wing assembly replaced, and get back out onto the track on the lead lap.
Castroneves is currently in 21st, and Sato is in 25th.