A driver died Friday after he was ejected from his car during a rollover crash in an unincorporated part of Alameda County, according to the California Highway Patrol. 

The driver, who was not wearing a seat belt, was ejected from his vehicle on Palomares Road around 3 p.m., a CHP spokesperson said Saturday. He was pronounced dead at the scene.

Authorities believe the crash was caused when the victim, whose age and identity have not been released, suffered a medical emergency.

No one else was injured in the crash.