ANGEL ISLAND STATE PARK — 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.

“It’s looking really good now,” said fire spokeswoman Sandy Wargo. “Weather is going to dictate how quickly the fire is contained.”

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 we had.”