ANGEL ISLAND, Calif. -- Firefighters made significant progress Monday against a wildfire that charred more than half of San Francisco Bay's largest island but spared scores of historical structures, some dating back to the American Civil War.

The blaze on Angel Island, which had spread to 380 acres since it started around 8 p.m. Sunday, was 75 percent contained by Monday afternoon, state park officials said.

Officials expected full containment of the fire by 6 p.m. Tuesday.

"Firefighters have initiated the mop up and are extinguishing the remaining hot spots," said Marin County Fire spokesman Mike Giannini.

More than 250 firefighters, about 20 fire engines and other equipment were ferried to the 740-acre island by boat and barge to corral the blaze. No injuries have been reported.

The wildfire started near some campsites and forced the evacuation of about 30 campers Sunday night, officials said. The cause of the wildfire is still under investigation.

The island off Marin County is home to more than 120 historical structures, including a military garrison built during the Civil War and an immigration station that was the first stop for millions of immigrants, mostly from China, in the early 1900s. It's also a popular hiking and biking destination easily accessed by ferry from nearby Tiburon.

The fire destroyed one abandoned water tank, but none of the island's historical structures have been damaged, said park superintendent Dave Matthews. Power to the island had been cut off for safety reasons.

"Many of the historical buildings were threatened. That would have been a significant loss to the cultural history of California," Matthews said. "Fortunately, the firefighters saved what he had."

Shooting flames and plumes of heavy smoke streaming from the island could be seen from miles away, and the smell of charred vegetation permeated surrounding communities.

On the island itself, helicopters dropped water on open flames Monday, while firefighters cleared brush and dug fire lines against the backdrop of the San Francisco skyline and Golden Gate Bridge.

The island, which is a state park, would be closed to visitors for at least one to two weeks, Matthews said. The park had planned to give journalists a preview of a $15 million restoration of the Angel Island Immigration Station on Tuesday, but that event was canceled.

Officials said it was the largest wildfire on the island that they could remember. The last major fire burned 25 acres three years ago.

The fire will eventually help rejuvenate the island's chaparral and woodland ecosystems, but could leave the land vulnerable to erosion and mudslides during the winter rainy season, Matthews said.

Park officials planned to search the charred grounds for cultural artifacts such as old cannonballs and horseshoes that may have been uncovered by the fire, he said.