A small fire in the cargo area of a truck loaded with batteries snarled traffic on the eastbound direction of the Dumbarton Bridge for about an hour Wednesday afternoon, said a spokesman for the California Highway Patrol.

No one was injured.

About 4 p.m. the driver of the truck noticed smoke wafting from the cargo area and pulled the vehicle to the right shoulder to await CHP and fire crews.

Crews arrived and doused the fire, quickly extinguishing it, said CHP spokesman Officer Colton Kropp.

The number 2 and number 3 lanes were blocked for about an hour while crews worked. The truck, which had been traveling on the bridge decline just inside Alameda County, was not severely damaged and the driver drove it away from the scene, Kropp said. The cause of the fire was not immediately known late Wednesday.

Follow Kristin J. Bender at Twitter.com/kjbender.