A 38-year-old man from Hayward died in a crash on southbound Interstate 680 in Walnut Creek early Friday morning, according to the California Highway Patrol.
The crash happened around 2 a.m. just north of Treat Boulevard, the CHP said.
The man crashed into a dump truck, rolled his car and eventually slammed into the concrete center wall, according to the CHP. He was pronounced dead at the scene.
It appeared that the man was not wearing a seat belt, the CHP said. Alcohol bottles were found in the man's car, but the CHP said it is not known at this time if alcohol and/or drugs played a role in the crash. An investigation is ongoing.
The driver of the dump truck was not hurt, according to the CHP.