Armando Hernandez, a 31-year-old Antioch resident, was driving Mitsubishi Diamante north on I-680 just south of Concord Avenue when he came upon the two mattresses in the roadway at 12:05 a.m.
Hernandez swerved to avoid the mattresses, lost control of his vehicle and crashed into the center divide, Yox said. The impact caused the car's electrical system to go out, leaving it dark.
Hernandez may have also crashed into a Ford Mustang that was also swerving to avoid the mattresses, Yox said.
Moments later, a Cadillac came along and crashed into the dark Mitsubishi.
Hernandez, who may have taken off his seatbelt to get out of his car, was ejected from his vehicle and killed.
The four people in the Cadillac suffered only minor injuries and the two people in the Mustang were not injured, Yox said.
The highway was closed for about three hours while the CHP investigated the crash.
The owner of the mattresses has not come forward. According to Yox, spilling a load on a highway can be either a misdemeanor or an infraction, depending on the circumstances. The penalty increases when the spill causes a crash.