Tony Stewart says the crash that killed 20-year-old Kevin Ward Jr. on a dirt track in upstate New York was "100 percent" an accident.

Stewart spoke to The Associated Press on Thursday from his home in Huntersville, North Carolina. It was his first interview since a grand jury decided against charging the NASCAR star in Ward's death. Stewart could still face a civil lawsuit.

Stewart says during his three-week hiatus from racing after the crash, he stayed in seclusion at his other home in Indiana and didn't want to get out of bed or even leave his room. He asked for professional help to deal with his grief.

Stewart said: "I know 100 percent in my heart and in my mind that I did not do anything wrong. This was 100 percent an accident."