A car trying to pass a group of motorcycles caused another car to lose control on a desert highway on Saturday, leading to a crash that killed five people and injured six others, officials said.
Seven motorcycles were caught in the collision on two-lane Route 98 near Ocotillo, a few miles(kilometers) north of the Mexico border and 80 miles (128 kilometers) of San Diego.
Two men and two women motorcyclists died at the scene before paramedics arrived, Imperial County Fire Department Capt Peter Stanton told The Associated Press.
One passenger from a car was also killed.
Stanton said the crash occurred shortly before 1 pm as an eastbound car went into the oncoming lane to pass about a dozen motorcycles, some of them carrying two people. That maneuver forced a westbound sedan to swerve on to the sandy shoulder to avoid a head-on collision.
He said at that point the westbound car veered back across the road and into the cyclists.
"He lost control and then his vehicle just drove into the group of motorcycles," Stanton said.
The eastbound car making the pass that triggered the accident did not stop and authorities were seeking it, Stanton said.
"They're looking for that car and the driver," he said. "He didn't stop, he kept going, he fled the scene."
Five people from motorcycles and one from a car were injured, Stanton said.
Several motorcycles toward the back of the pack were able to avoid the accident.
Two helicopters landed on the highway to airlift two male patients to San Diego-area hospitals, and four ambulances took patients to local hospitals in Brawley and El Centro, authorities said.
The identities of the dead and injured were not released.
The California Highway Patrol's Multidisciplinary Investigation team was called in from San Diego to lead the investigation because of the accident's size, CHP spokesman Pablo Torrez told the Imperial Valley Press.
Ocotillo is a tiny town in a border area best known for its frequency of earthquakes.