A 250-acre brush fire on Angel Island in Marin County is 20 percent contained, Marin County Fire Chief Mike Giannini said Monday morning.
Three helicopters are fighting the blaze and two air tankers are expected to join the air attack today, Giannini said.
Firefighters from around the Bay Area and some from as far away as Butte County have been called to assist, he said.
Giannini, speaking from a command center on Tiburon Boulevard in Tiburon, said there is still "a fair amount of wind that has laid the smoke down pretty well and some flames are still visible."
He estimated winds to be about 8-10 mph.
The fire is sending a glow visible across the San Francisco Bay.
Bright, orange flames started to illuminate the island around 9 p.m. on Sunday, prompting the evacuation of about 40 campers, Marin Co. Fire Chief Mike Giannini said.
Residents in San Francisco said they could smell the fire and watched the flames rapidly spread along major a length of the island's silhouette and over the its hillside within an hour.
Giannini, who is stationed at the Tiburon command center on the peninsula, said around 5:30 a.m. that smoke was pushing toward San Francisco and the fire was still "creating quite a sight for most folks around the Bay."
The primary concern is the East Garrison area because it contains historical structures, he said.
Fire crews have to travel to the island by boat and engines by barges but the biggest problem is the steep terrain and the wind, he said.
He said there is speculation that the fire may have started from a bonfire but he said the cause has not yet been determined.
"As soon as we get first light, we'll get an air attack up there and a good picture of what's still actively burning," he said.