According to the California Highway Patrol, one big rig truck was parked along the side of the freeway for an unknown reason.
Then, at around 4:10 a.m., a second big rig side swiped it. The impact was so strong both rigs flipped over.
"No they were not sleeping on the side of the road. They stopped momentarily, for what reasons, they are still under investigation," Sgt. Steven Lott of the California Highway Patrol said.
The back up reached all the way to the Midway Rd entrance, near Dixon.
CalTrans said clean up took a lot longer than normal, because the contents of the second big rig-- a scrap metal dump truck -- spilled all over the high way.
The number 3 and 4 lanes were closed until all the debris was cleared.
Despite the major damage to their vehicles, CHP said their drivers were extremely lucky.
The collision resulted in minor injuries. Both drivers of each of the big rigs, and a secondary driver, who was in the sleeping berths of one of the big rigs," Sgt. Lott said.