The fire, reported about 7:50 p.m., charred 3 to 4 acres of vegetation but did not burn any structures or cause any injuries, Lt. Mindy Talmadge said Monday.
Two eastbound lanes on the lower deck of the Bay Bridge were shut down as crews battled the blaze. Flames were visible to eastbound motorists, and those traveling west could see an orange glow around the island and a plume of smoke.
The fire began as people were leaving the 49ers game at Candlestick Park. Traffic was at a standstill for miles on northbound U.S. Highway 101.
Lanes on the bridge gradually reopened as crews gained the upper hand on the blaze, Talmadge said.
The fire, she said, appears to have started in the bottom of a ravine in a hard-to-reach area, making it likely “investigators will not even be able to access that area to make an absolute determination” of the cause. There is speculation that fireworks may have sparked the fire.