The latest shooting occurred around 8:45 p.m. Sunday on the northbound 5 Freeway near Euclid Street, according to the California Highway Patrol.
The driver, who was not injured, told authorities he was driving his mother home from church when shots were fired at his car from another vehicle, described as a black Ford Fusion.
No arrests have been made.
Two other recent shootings occurred in Irwindale.
Motorcyclist wounded, car struck after two shootings hours apart on 605 Freeway in Irwindale
About 11:25 p.m. Saturday, a motorcyclist was shot and wounded on the southbound 605 Freeway near Arrow Highway, the CHP reported.
Paramedics transported the victim, a man in his 30s from Azusa, to Los Angeles County/USC Medical Center with a single gunshot wound.
The CHP's Baldwin Park office urged anyone with any information regarding the shooting to call them at 626-338-1164.
Meanwhile, authorities were trying to determine whether the shooting was related to another one that also occurred on the 605 Freeway in Irwindale.
That incident was reported just hours earlier, at 5:13 p.m. Saturday on the southbound 605 Freeway at Lower Azusa Road, according to the CHP.
Shots were fired and at least one vehicle crashed, possibly due to the shooting, the CHP reported. No one was hurt.
City News Service contributed to this report.