Nascar star Tony Stewart has been left at a loss for words after accidentally hitting and killing another driver during a race in New York on Saturday (09Aug14).

Kevin Ward, Jr., 20, was fatally struck at the Canandaigua Motorsports Park in Ontario County after walking into the path of oncoming cars shortly after his own vehicle had spun off the track.

The tragic incident, which is being investigated by police, prompted Stewart to pull out of competing in the Nascar Sprint Cup Race on Sunday (10Aug14), and he subsequently released a statement expressing his shock at the unexpected turn of events.

The press release reads: "There aren't words to describe the sadness I feel about the accident that took the life of Kevin Ward Jr. It's a very emotional time for all involved, and it is the reason I've decided not to participate in today's race at Watkins Glen.

"My thoughts and prayers are with his family, friends and everyone affected by this tragedy."

The police investigation into the accident is not criminal and no charges have been filed against Stewart.