EL SOBRANTE -- Two people suffered major injuries and another person was hurt after a head-on crash that closed San Pablo Dam Road for more than an hour on Friday afternoon, police said.

Officers from the California Highway Patrol, the Contra Costa Sheriff's Office and East Bay Regional Parks Police responded at 4:26 p.m. to the roadway east of Castro Ranch Road for a report of a wreck involving two vehicles, CHP Officer Ralph Caggiano said.

Fire crews from Richmond, Moraga-Orinda Fire District and Contra Costa Fire Protection District also assisted.

The crash took place about five miles from Orinda and at least one person was extricated from one of the vehicles, Caggiano said. That unidentified person was taken by medical helicopter to John Muir Medical Center in Walnut Creek to be treated for critical injuries, Caggiano said.

Two other people were injured -- one who was also taken to a hospital in critical condition, according to Contra Costa Fire Protection District spokesman Robert Marshall.

The third victim was treated at the scene, Marshall said, but it was not immediately known if that person self-transported themselves to a hospital.

San Pablo Dam Road was closed in both directions until about 6 p.m., Caggiano said.

Contact Natalie Neysa Alund at 510-293-2469. Follow her at Twitter.com/nataliealund.