The bus, which was carrying 47 passengers in addition to the driver, was traveling on California Highway 99 when it encountered what appears to have been a previous accident involving an overturned SUV in the fast lane. According to an eyewitness, the bus swerved at the last minute but struck the SUV, and then struck a second vehicle.
Taxi driver Mike Coupland, who witnessed the accident, told CNN affiliate KMPH-TV "at the last second" he saw the SUV on its side in the highway -- "no lights, no nothing." He said the bus did not have time to stop before striking the SUV.
All three vehicles went down an embankment, and the bus slammed into a large eucalyptus tree. "The impact was like a bomb going off," Coupland said. "Just pieces and parts everywhere."
Four women and two men died, including the bus driver and one person in the SUV.
The Greyhound was en route from Los Angeles to Sacremento. The accident occurred at 2:15 am PDT.