The fire was reported shortly after 10 a.m. on the bridge at the Marin-Contra Costa county line, according to the CHP.
Both eastbound lanes were initially blocked as crews responded, and one lane reopened around 10:30 a.m.
The fire, which is now out, resulted in a diesel spill, CHP Officer Marc Johnston said. It is unknown how much spilled.
All lanes were reopened by 2 p.m.