The California Highway Patrol was investigating the cause of a crash involving at least eight big-rigs on rain-slicked Interstate 5 in the mountains north of Los Angeles.
Three people received minor injuries in the Monday night collision in the southbound lanes of the I-5 truck tunnel near State Route 14, authorities said.
Four tankers containing gas, crude oil, milk and chemicals, were involved in the crash, but none ruptured, Los Angeles Fire Department Erik Scott said.
KCAL-TV footage showed a tangle of trucks and traffic backed up behind them for miles.
Dozens of firefighters from Los Angeles city and county initially responded to the scene, along with California Highway Patrol officers.
It had been raining throughout the day in the Los Angeles area, but it wasn't known if weather contributed to the crash, authorities said.
The pileup occurred near the site of a deadly chain-reaction crash in 2007 that involved more than two dozen vehicles and left three people dead. A truck driver speeding on the rain-slicked interstate _ the major West Coast route between Mexico and Canada _ lost control and crashed into a median barrier in the truck lane tunnel, setting off the crashes and sparking a deadly inferno, investigators concluded.
The 2007 collisions closed the busy highway for two days and cost $17 million to clean up and repair.