The fire was reported around 1:30 a.m. on the 2,100-acre island, according to the East Contra Costa Fire Protection District. As of 5 a.m. the fire had burned 212 acres and two structures, but no injuries were reported.
An estimated 15-25 people live on the island and the fire district helped three people evacuate, said Fire Marshal Steve Aubert.
The remaining residents have decided to stay and fight the fire on their own, he said.
The island is outside any fire district's jurisdiction and fire officials are letting the blaze burn since it's surrounded by water on all sides. Firefighters will respond in life-threatening cases, Aubert said.
The island is a reclaimed peat wetland that's only accessible by boat. In July 2010, a fire burned or smoldered for nearly a week on the island.
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