Tony Stewart no stranger to track incidents

A police investigation into what happened at a NASCAR race at Canandaigua in upstate New York is under way after a 20-year-old driver named Kevin Ward Jr. was killed when he got out of his vehicle. He was run over by three-time NASCAR champion Tony Stewart.

On the 14th lap of the Super Sprint Race, Ward's no. 13 car was on the outside portion of the track when Stewart, in the no. 14 car, squeezed Ward into the wall, causing him to spin out and blow a tire. Ward then got out of his car and began walking along the track, gesturing as Stewart's car neared.

A video shows Stewart's car running Ward over. (WARNING: Video of the incident at left may contain images some viewers find upsetting.)

Medics arrived within seconds. Ward, who had been racing Sprint cars since 2010, was pronounced dead an hour later by doctors at a nearby hospital.

"As we speak at this time, there is no evidence in hand, or no facts that would support a criminal charge or support criminal intent," said Ontario County Sheriff Phillp C. Povero, who is overseeing the investigation.

But the incident has raised questions about whether Stewart's actions were deliberate.

"I think he is an aggressive driver but not like that. I mean when they say an aggressive driver, maybe he is battling for position, or blocking a guy," said Jeff Gluck, who covers racing for USA Today." But to take a guy out like that...I think that is a whole new level of classification."

Stewart was still angry shortly after a helmet-throwing incident two years ago and made a statement that could come back to haunt him: "I checked up twice not to run over him. And I learned my lesson there, and I'm going to run over him every chance I got until the end of the year. Every chance I got."

Stewart, nicknamed "Smoke," was involved in an accident last year at the same track. He only returned to racing in February after losing the rest of last season when he suffered a broken leg in a dirt track race last year in Iowa.

Initially Stewart's team manager said Stewart planned to race at today's NASCAR event at Watkins Glen. Greg Zipadelli was quoted as saying "we're business as usual," which angered some. The team later reversed position.

"This is a very tough ... emotional time for everybody," said Zipadelli. "With that being said we feel that as a group Tony will not drive today."

On Sunday, Tony Steward released a statement that read in part: "There aren't words to describe the sadness I feel about the accident took the life of Kevin Ward Jr. My thoughts and prayers are with his family, friends and everyone affected by this tragedy."