CHP officials said four motorists called in reports between 2:30 p.m. and 9 p.m. on Monday after their rear windshields were shattered.
One incident happened at 2:23 p.m., on the southbound 405 at Mulholland. Officials said it was not clear if the windshield was shattered by a shot or a rock.
Another call was received at 8:04 p.m., when the rear window of a vehicle traveling northbound on the 405 at Culver was shattered. Again, officials had not determined whether the windshield was shattered by a rock or a shot.
At 8:21 p.m., the driver of a vehicle traveling northbound on the 405, also at Culver, called to report a similar incident.
The fourth incident happened during the same time period, NBC4 reported.
Officials said the vandalism appeared to be random. None of the victims was able to describe the assailant or assailants.