A mountain biker riding at Annadel State Park had a heart attack and died Saturday afternoon, according to a park ranger.

The man, who was believed to be in his 60s and from Santa Rosa, died on Marsh Trail, said Neill Fogarty, supervising ranger.

The call for assistance came a little before 3:30 p.m., Fogarty said. He was about to set out on Richardson Fire Road with rescue workers from Bennett Valley Fire Department when they heard that the Sheriff's helicopter Henry 1 had reached the victim.

The man, whose name was not immediately released, was believed to have died at the scene, Fogarty said.

"I really feel for the family," Fogarty said. "It's three days after Christmas."

Annadel State Park, which sees about 1,000 mountain bikers a day, can be a difficult workout because of the rugged terrain, he said.

"It's happened before up here. It's pretty strenuous and rigorous," Fogarty said.

Dispatchers at the Sheriff's Office did not immediately release information about the accident.

You can reach Staff Writer Cathy Bussewitz at 521-5276 or cathy.bussewitz@pressdemocrat.com.