UPDATE 11:55 a.m: Saddened to learn that the cyclist died in this incident. Unclear if crash or prior medical incident contributed to death.
Park rangers and crews of firefighters responded to a call for help at the summit of Mount Diablo State Park Thursday after a lone bicyclist suffered critical injuries in a crash there.
Rangers and firefighters responded to the area near the Summit Visitor Center after the incident was reported at 11:52 a.m. An air ambulance crew brought additional help to the scene shortly afterward.
The victim, whose age or gender was not immediately known, was reportedly receiving life-saving measures at the scene.