Tony Stewart speaks of sadness following fatal collision

According to authorities and eye-witness accounts, the three-time NASCAR Sprint Cup Series champion hit and killed Ward Jr. who had walked towards Stewart's car after the two had an altercation during a race at Canandaigua Motorsports Park.

The Ontario County (N.Y.) Sheriff"s Office confirmed in a news release that Ward Jr. had been declared dead 45 minutes after the incident upon arrival at Thompson Hospital.

Some reports suggested that Stewart would still take part in Sunday's Cheez-It 355 Sprint Cup Series event in Watkins Glen, New York, but Stewart-Haas Racing vice president of competition Greg Zipadelli confirmed the 43-year-old's withdrawal earlier in the day.

And Stewart has now released his own brief statement.

"There aren't words to describe the sadness I feel about the accident that took the life of Kevin Ward Jr.," it read.

"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 everyon affected by this tragedy."

In relation to Saturday's tragedy, Sheriff Philip C. Povero had earlier told reporters: "Right now, this is an on-track crash investigation.

"There are no criminal charges pending at this time. We are not making any inferences of any criminal conduct at all.

"He [Stewart] was visibly shaken by this incident and promised his continuing cooperation of this investigation."