Four US motorcyclists have died when a car slammed into them as they took part in a ride to celebrate their club's 10th anniversary.
The driver was arrested for being over the alcohol limit, but was not blamed for the accident because another car caused him to swerve into the riders.
The second car drove off from the scene on a desert road outside San Diego, California, and has not been traced.
The dead included a husband and wife who were on the first motorcycle to be hit.
Carl Smith, president of the Saddletramps Motorcycle Club, said three other riders were seriously injured but were expected to survive. Two others had less serious injuries.
The group was riding together when a Honda Civic passed them, forcing an oncoming car off the road and then it veered back and into the group.
None of the motorcyclists got the Honda's number plate and none of the survivors pursued him, choosing to stay behind to help their friends.
Car driver Carlos Ramirez Bobadilla, 36, whose passenger also died in the crash, was arrested when officers smelled alcohol on his breath.
It was unclear whether his drinking contributed to the collision, police said, but he was not being held responsible for the deaths based on evidence collected so far.