A 31-year-old man died in a dirt bike crash at a Jordan River state park for off-road vehicles Saturday, police said.

Brian Buttars of Lehi was going over a double jump on a motocross track when he crashed his dirt bike about 12:30 p.m., said Salt Lake County Sheriff's Lt. Don Hutson. He was wearing full protective gear, but suffered traumatic injuries and went into cardiac arrest. Buttars was pronounced dead at the park, which is located at 2800 N. Rose Park Lane (1935 West).

The bike was found at the bottom of the second of the two jumps. Deputies are investigating what caused him to crash.

"It was not witnessed by anyone," Hutson said. "There were other people at the park, but no one in that immediate area."

Buttars was at the park with friends, riding on one of the more advanced of four dirt tracks, said Bob Rosel, a park manager with the Utah Department of Natural Resources. There was also a fatal accident at the park in 2002.

After they heard about the crash, two other riders, 26-year-old Craig Thomas, of Bluffdale, and 28-year-old Paul Hansen, of Herriman, decided to leave the park for the day.

"When you find out someone died, as a rider, he would have wanted you to keep riding. That's what I would want," Thomas said. "In a second sense, you want to have respect for his family."

"I hate to see this happen, but it's kind of part of the game. There's always that risk," Hansen said.