Stewart was trying to drive underneath Landon Cassill when Cassill spun on the backstretch, forcing Stewart to lift and get hit from behind by Regan Smith.
Several cars were damaged in the chain-reaction crash, including those of Stewart, Cassill, Smith, Juan Pablo Montoya, Casey Mears, Scott Speed, Stephen Leicht, Reed Sorenson, David Gilliland, Dave Blaney, David Reutimann and Michael McDowell.
The 12-car crash was the biggest of the year in a season that seen fewer wrecks than in recent years.
Stewart eventually returned to the track after spending 65 laps in the garage.
“The No. 83 (of Cassill) was trying to get back down to the bottom and we were just in the wrong place at the wrong time,” Stewart said. “It wasn’t Regan’s fault.
“He was right behind us and he didn’t have anywhere to go either. (It’s) just not a real good deal at the beginning of the race like this.”
Stewart had a poor qualifying effort as he had started 29th and was trying to work his way through the field.
Source Sporting news.com