CASTRO VALLEY -- A motorcyclist died after a collision with a truck Wednesday afternoon, a spokesman for the California Highway Patrol said.

The name, age and city of residence of the rider was not immediately available.

The crash occurred about 4:40 p.m. in the 26000 block of Palomares Road at Paloverde Road. Witnesses stopped and performed CPR, but the motorcyclist died at the scene, the CHP spokesman said.

The scene has been cleared.

No one else was injured and the driver of the truck cooperated with authorities.

Information on the type of truck that struck the biker or the circumstances around the collision were not immediately available.

Check back for updates.

Reach Kristin J. Bender at kbender@bayareanewsgroup.com. Follow her at Twitter.com/kjbender.