RICHMOND -- Three people were injured -- two seriously -- after they were thrown from an off-road vehicle that rolled over on a steep trail near Kennedy Grove Regional Park on Sunday afternoon, authorities said.

The two most seriously injured people were taken by helicopter to John Muir Medical Center in Walnut Creek, according to Battalion Chief Lon Goetsch of the Contra Costa County Fire Protection District. The other person was transported by ambulance. Their conditions and identities were not released Sunday night.

Rescuers had to use four-wheel drive vehicles to approach the site of the crash, then hiked up a steep hillside to reach the victims, Goetsch said. A California Highway Patrol helicopter and a crew from Richmond Fire Department also responded.

The helicopter used its winch to lift the two more seriously injured victims out of the crash site before they were transferred to a medical helicopter.

There was no information immediately available about the cause of the crash.

Contact Daniel M. Jimenez at 510-262-2728. Follow him at Twitter.com/DMJreports.