NASCAR driver Tony Stewart is under investigation after a deadly accident on a dirt track in upstate New York left another driver dead.

Police in Canandaigua, N.Y. said Stewart hit fellow driver Kevin Ward Jr., 20, who had exited his car during a sprint car race.

According to witnesses, Stewart spun out Ward during the race, CNN reports.

Ward got out of his car and walked on the track, where he was hit.

Ward was taken to the hospital where he later died.

Stewart was questioned and released after the incident, and a spokesperson issued the following statement on Sunday:

“A tragic accident took place last night during a sprint car race in which Tony Stewart was participating. 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.”

Stewart was set to race at Watkins Glen on Sunday, but has reportedly decided to pull out of the race.