Mayor Jimmy Delshad told the Los Angeles Times and KNBC-TV late Thursday that police believe the shooter fired into Ronni Chasen's passenger-side window from another vehicle and not from the street or a sidewalk.
He says detectives believe the bullets came from an SUV because of the high angle of shots fired.
Delshad said police found some pieces of glass - possibly from Chasen's car window - near the shooting site, but found no bullet casings.
Chasen was shot to death early Tuesday in her Mercedes-Benz while driving home from a premiere after-party for the film "Burlesque."
Police say they have no motive and no suspects.