Police and firefighters responded to the scene of a fatal collision involving a motorcycle on northbound I-680 just north of El Cerro Boulevard a little after 8 p.m. Sunday.
Officers said the unidentified male rider of a red 2004 Honda CBR motorcycle was located in the roadway and declared deceased at the scene.
A CHP spokesman said another vehicle that may have struck the rider after he was down on the roadway remained on scene and that party was fully cooperative throughout the investigation. Additional possible witnesses also remained on scene to aid in the investigation.
A traffic sigalert was issued shortly after the collision, shutting down all lanes of I-680 northbound but the center median and fast lane opened shortly thereafter to allow traffic to continue northbound while the investigation took place.
This incident is still under investigation. If anyone witnessed this collision or the events leading up to it, please contact Contra Costa CHP in Martinez at (925) 646-4980.