The truck caught fire about 6:30 a.m. along westbound Highway 84 just past the toll plaza, according to the California Highway Patrol.
The truck may have hit a guardrail before catching fire, the CHP said.
The driver suffered minor injuries and was taken to a hospital as a precaution, but no other injuries were reported.
A Sig Alert was issued soon after the truck fire was reported and the bridge was closed to westbound traffic.
All lanes were reopened as of 2:10 p.m.
The CHP said that the right lane would be closed for six hours, starting at 3 p.m., for repairs to the guardrail.
Stay with ABC7 News for updates on this developing story.