MARTINEZ -- A man killed in a solo car crash Saturday on Highway 4 was identified as a 41-year-old Pittsburg man, authorities said Monday.

Ronald Aguirre died after crashing at 5:33 a.m. No one else was injured, but authorities shut down the eastbound Pacheco Boulevard on-ramp for nearly two hours. The cause of the crash remains under investigation.

David DeBolt covers breaking news. Contact him in Richmond at 510-262-2728. Follow him at Twitter.com/daviddebolt.