One woman was killed in the accident. Police believe she was killed after she got out of her car and was struck by another vehicle.
The accident happened after 8 a.m. in northbound lanes near the Vietnam Veterans Memorial Bridge over the Sacramento River, 10 miles north of downtown. Dense fog reduced visibility to less than 30 feet, the California Highway Patrol said.
Smashed cars, motor homes, light trucks, big-rigs, and even snowmobiles were scattered over a tenth of a mile in southbound lanes. A sport-utility vehicle sat sandwiched between two tractor-trailers, both of their cabs burned. Another small truck came to a rest on top of a car. Three snowmobiles thrown from another vehicle lay in the freeway.
Marie Nicholson, 39, scrambled from her car during the pileup. She said she veered into the median to avoid striking other vehicles.
"I heard tires screeching, so I peeled off into the median because a truck was barreling down on me," she said. "I got out of my car and ran." The truck continued to bear down but didn't hit her car.
"People were hysterical," she said. "There was a truck on fire and we were afraid it was going to blow up. There were people trapped, but they got them out."
Ten people were taken to hospitals, three with serious injuries, California Highway Police Officer Reid Thompson said.
Such chain-reaction pileups are common this time of year, when heavy fog descends on California's Central Valley.