The collision between the big rig and a Buick sedan was reported at about 12:55 a.m. just west of Schaefer Ranch Road on Highway 580 west of Dublin, according to CHP Officer Steve Creel.
The sedan, occupied by three men in their 40s who were traveling from Southern California, was parked on the right hand shoulder when the big rig struck it from behind, causing it to go forward and overturn, Creel said.
One passenger was ejected from the vehicle upon impact, and suffered major lacerations to his head. The 43-year-old driver was trapped in the vehicle and complained of abdominal pain after being extracted from the vehicle by authorities, Creel said.
A man in the backseat of the sedan also complained of minor pain, Creel said.
The Safeway big rig also overturned, blocking the right side of the highway. The 50-year-old driver of the big rig was knocked unconscious in the collision and suffered a contusion to his head, according to Creel.
All four men involved in the collision were transported to Eden Medical Center to be treated for their injuries, according to Creel.
The towing of the big rig was complicated because of the contents in its trailer. The supermarket produce had to be unloaded to a separate trailer before the truck was towed, CHP Officer Robert Haven said.
The truck was taking produce items from Safeway's depot in Tracy to stores in Oakland, Creel said.
A small spill of about 20-25 gallons of diesel fuel also had to be cleaned up at the scene, according to CHP Officer Ralph Caggiano.
The collision had three of the highway's four westbound lanes blocked for much of the morning.
A Sig-alert was issued at about 1:10 a.m. and all lanes were clear around 9:45 a.m., Caggiano said.