CANANDAIGUA, N.Y. -- NASCAR driver Tony Stewart struck and killed sprint car driver Kevin Ward Jr., who had climbed from his car and was on the track trying to confront Stewart during a race in upstate New York on Saturday night.
Stewart was unhurt.
Stewart will not race Sunday in an event that is critical for his championship chances.
Greg Zipadelli, competition director for Stewart-Haas Racing, said the three-time NASCAR champion "feels strongly" he should not race at Watkins Glen following Kevin Ward Jr.'s fatal accident.
Regan Smith will replace Stewart in the car.
Ward had climbed from his car on the darkened dirt track and was trying to confront Stewart when he was struck Saturday night.
Ontario County Sheriff Philip Povero said his department's investigation is not criminal and that Stewart was "fully cooperative" and appeared "very upset" over what had happened.
"He was visibly shaken by this accident," Povero said. "... This is right now being investigated as an on-track crash and I don't want to infer that there are criminal charges pending. When the investigation is completed, we will sit down with the district attorney and review it. But I want to make it very clear: there are no criminal charges pending at this time."
A video of the crash at Canandaigua Motorsports Park showed driver Ward, wearing a black helmet and firesuit on a dimly lit track, walking toward Stewart's car before being hit and hurtled 50 feet. Povero said the the 25-lap race was under caution when Ward was struck. Stewart's car was behind another before he hit Ward.
"The first car swerved to avoid the driver," Povero said.
Ward, 20, was pronounced dead Saturday night at a hospital in Canandaigua.
Stewart-Haas Racing, of which Stewart is a co-owner, released a statement early Sunday morning.
"A tragic accident took place last night during a sprint car race in which Tony Stewart was participating," the statement read. "Tony was unhurt, but a fellow competitor lost his life. Our thoughts and prayers go out to his family and friends. We're still attempting to sort through all the details and we appreciate your understanding during this difficult time."
Povero said the 43-year-old Stewart, a three-time NASCAR champion and frequent competitor at local sprint car events, was questioned and released. The sheriff is asking for people who have video of the crash to contact the office so copies can be obtained for review.
"People that witnessed it were horrified," Povero said of the crash. "They were extremely shocked."
Video of the crash showed Ward, in the No. 13 car, spin into a wall after contact with Stewart's car. The video showed Ward climb quickly from his car and briskly walk around it in what appeared to be an attempt to confront Stewart as he passed by in his own car, Stewart's familiar No. 14.
The video showed Ward to the right of Stewart's car, which seemed to kick out from the rear and hit Ward. The driver was hurtled through the air and emergency personnel quickly reached Ward as he lay on the track.
Michael Messerly, a fan who witnessed the crash, said it appeared Stewart struck the driver as he tried to speed past him.