Doris Peniche with the California Highway Patrol said the accident happened around 4:10 a.m. as a Caltrans worker was pulling in reverse with the emergency lights on to pick up cones from an ongoing closure. For unknown reasons, the van rear-ended the truck at Peck Road in El Monte.
Authorities said the victim in the accident was in his late 20s to early 30s. He was from Arizona but lived in California. The release of his identity was pending notification of kin.
The California Highway Patrol says the driver was travelling at freeway speeds when he hit the truck. Two workers, one on the back of the truck and a driver, received minor injuries.
"The good thing is the back-up truck is a heavy-duty truck, so the long tail absorbed the brunt of the impact," said Peniche.
The accident backed up traffic into West Covina during morning rush hour. Conditions on the freeway have since returned to normal.
This comes just days after two suspected drunk drivers hit each other and then slammed into a construction zone on the 405 Freeway, killing road workers Ramon Lopez and Ricardo Zamora. There have been at least four accidents involving freeway workers this year alone.
Under California law, vehicles must slow down and move over for any crew with flashing yellow lights.
"Slow down, move over for the cones, just pay attention, slow down, don't text and drive, don't drink and drive," said Peniche.
CORRECTION: It was earlier reported that a Caltrans contracted worker was killed in the crash. Authorities say two Caltrans workers suffered minor injuries. Also, in an earlier report, we incorrectly listed Carlos Zamora as the name of one of the road workers killed on Sunday, instead of Ricardo Zamora.