ALAMEDA COUNTY (CBS SF) — One person was killed and another seriously injured Saturday morning when a car plunged about 400 feet off of Redwood Road near Castro Valley and Upper San Leandro Reservoir, the Alameda County Fire Department said.

Emergency responders were called at 9:08 a.m. Saturday to Redwood Road near the Bort Meadow Staging Area in the Anthony Chabot Regional Park, ALCo Fire said. There they discovered a car had gone off the road toward the water.

One person in the car was pronounced dead at the scene; the victim’s name was not available Saturday night. The second victim was taken by California Highway Patrol helicopter to John Muir Medical Center in Walnut Creek with serious injuries.

The accident remained under investigation late Saturday.