The box truck landed on its cab along northbound I-680 in Pleasant Hill.
The accident blocked the freeway's two right lanes.
Anna Manchester tells ABC7 she was driving in the fast lane on northbound I-680 just around 9:30 a.m. when she lost control of her vehicle and swerved into the box truck, flipping it over.
"I'm flabbergasted, I don't know, it was the craziest thing ever," she said. "It was really frightening. I was just hoping he was OK."
The driver of the box truck, Felimon Ruiz, was making a delivery at the time. He said he saw Manchester coming at him but didn't have time to react, and just focused on staying alive during the initial crash and afterward.
"I was just praying that nobody would come and hit me once I was on the floor already, when everything stopped," he said. "I still can't believe it. It looks like a movie or something."