Tony Stewart completely snapped.

The former NASCAR star was signing autographs at a dirt track in Jackson, Minnesota, over the weekend when he ran toward a heckler and socked him right in the face, as shown in video posted on social media.

Stewart was driving in a sprint car race at the Jackson Motorplex when his engine blew after the first lap, according to TMZ. He then signed autographs for fans, but one fan reportedly was furious at Stewart and accused him of bailing from the race on purpose.

“F–k you, Tony,” the fan said, according to TMZ. “You piece of s–t. You come here and basically race for one lap and quit, you piece of s–t.”

Stewart reportedly responded by saying, “I blew my engine, you f–king a–hole. Do you want to pay for it?”

In the video, Stewart can be seen giving the middle finger to the fan and telling him to “f–k off.” The heckler then says, “Hey Tony, I’ve got two of them.”

That’s when Stewart lost it and ran right to the heckler and punched him in the face. Citing a witness, TMZ says Stewart thought he broke his hand and cops weren’t called as track officials dealt with the situation internally.

Other fans seemed pleased about what Stewart did. One person screamed at the heckler, “F–k you, bitch!” while another said, “Atta boy!” Another can be heard saying, “Way to go, Smoke,” using Stewart’s nickname.

No longer an active NASCAR driver, Stewart is a co-owner of Stewart-Haas Racing. The three-time NASCAR Cup Series winner is set to enter NASCAR’s Hall of Fame next year.