CANANDAIGUA, N.Y. >> NASCAR driver Tony Stewart struck and killed a driver who was walking on a dirt track during a race in upstate New York, authorities said early Sunday.

A video of the crash at Canandaigua Motorsports Park showed driver Kevin Ward Jr. stepping toward Stewart’s car before being hit and hurtled 50 feet.

The Ontario County Sheriff’s Department would not identify the driver but said he was pronounced dead Saturday night at a hospital in Canandaigua.

Sheriff Philip Povero said his office is not investigating the incident as a criminal matter. He said Stewart, 42, was “‘fully cooperative” while being questioned and released.

Calls to Stewart’s representatives were not immediately returned. The three-time NASCAR champion is scheduled to race in NASCAR’s event Sunday at Watkins Glen.

Michael Messerly, a fan who witnessed the crash, said it appeared Stewart hit the driver as he was walking on the dimly lit track after they had collided on the previous lap.

He said the driver was wearing a dark racing suit as Stewart’s car passed him.

“I didn’t see (the other driver) anymore,” he said. “It just seemed like he was suddenly gone.”

Messerly said the crash appeared to be the result of “a number of bad decisions” and not “any intent on Tony Stewart’s part.”

“Auto racing is a dangerous sport,” he said. “I think it was just an unfortunate set of circumstances that created a tragic situation.”

The track, about 30 miles southeast of Rochester, canceled the remainder of the race within five minutes and later posted a message on its Facebook page encouraging fans to “pray for the entire racing community of fans, drivers, and families.”