BRENTWOOD (CBS SF) — A bicyclist suffered major head injuries Saturday morning after colliding with a car near the Los Vaqueros Reservoir in eastern Contra Costa County, authorities said.

The 28-year-old woman was wearing a helmet when her bike collided with the vehicle about 8:30 a.m. just inside the reservoir and watershed area, near Walnut Boulevard and Camino Diablo, according to East Contra Costa Fire Protection District Battalion Chief Craig Auzenne.

Los Vaqueros Reservoir

Rainbow over Los Vaqueros Reservoir in Contra Costa County

Emergency crews provided care at the scene and the woman was airlifted to John Muir Walnut Creek Medical Center with major head and shoulder injuries, Auzenne said.

The cause of the collision is under investigation.

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