A cyclist suffered major head injuries Sunday after he crashed into a stopped truck while traveling downhill near Glen Ellen, the CHP said.

Cyclist James Casciani, 56, of Santa Rosa was heading east on Sonoma Mountain Road just before 2 p.m. when he encountered a flatbed truck approaching from the opposite direction, CHP Officer Marcus Hawkins said.

Truck driver Gerard Anger, 43, of Napa "stopped because he saw the bicyclist coming," but the cyclist appeared "unable to stop," Hawkins said.

Casciani crashed into the 11-ton winery truck, cracking the fiberglass hood of the vehicle and suffering major head injuries, Hawkins said.

An ambulance crew placed the man on a stretcher and took him to a spot where a REACH medical helicopter could land.

Casciani was flown to Santa Rosa Memorial Hospital and remained at the hospital late Sunday, Hawkins said.