Man Hurt During Freeway Shooting : Crime: Santa Monica Freeway is tied up for hours. A witness says occupants of two cars argued before shots were fired.

A dramatic daylight shooting incident on the Santa Monica Freeway in West Los Angeles left a motorist hospitalized in serious condition Saturday when his car careened into the center divider and overturned.

Westbound traffic was tied up for five hours as police investigated.

A motorist who saw the incident unfold in his rear-view mirror told police that it was apparently started by a driving dispute among occupants of two cars.

“They exchanged some gestures,” said Los Angeles Police Detective Charles Brown. “Then the witness heard . . . several shots.”

Authorities said Jeffrey Johnson, 20, was shot at by occupants of the second vehicle as he drove westbound near the Robertson Boulevard off-ramp about 9 a.m. Police did not disclose Johnson’s address.

Johnson, who apparently was not struck by the gunfire, suffered severe head injuries from the crash.

Police said they recovered a semiautomatic handgun in Johnson’s new black Ford Escort, but said it was unclear whether the driver, who had no passengers in his car, traded shots with his assailants.

Johnson’s car was struck in the rear by at least one bullet before it hit the center divider of the freeway, which had little traffic on Saturday morning.

Dan Lambirth, a nearby resident who was driving on a surface street next to the freeway, said he heard “eight to 10 gunshots go off” in rapid succession.

When authorities arrived, they found the victim’s car flipped on its roof and straddling the fast lane.

Los Angeles Fire Department paramedics took Johnson to Cedars-Sinai Medical Center, where he underwent surgery for several hours. A hospital spokesman said he was in serious condition in the intensive care unit.

Police described the fleeing vehicle as an older American-built car with a white top, dark body and vertical tail lights. It contained three or four occupants.

A bullet casing was recovered by police near the Robertson Boulevard off-ramp, about 150 yards behind where Johnson’s car came to a stop.

Two lanes of the westbound Santa Monica Freeway were shut for five hours, resulting in a SigAlert as traffic backed up several miles to Crenshaw Boulevard.

Los Angeles Police detectives did not arrive at the scene to inspect the car for almost three hours. Authorities said the delay was because detectives assigned to the West Los Angeles station are on call on weekends and must be summoned from their homes, which are as far as Valencia.