A wildfire that broke out on an island in the Channel Islands national park has become California’s largest wildfire so far this year, burning through more than 10,000 acres, destroying historic structures and endangering rare plant communities that conservationists had struggled to reclaim.

About six dozen firefighters have been deployed to control the blaze, which broke out on Friday, but their efforts have been undermined by strong winds. The fire is now at 0% containment, according to a Cal Fire incident report.

The fire on Santa Rosa Island appears to have started after a sailor crashed his boat against the rocks on the shore of the island, leaving him stranded. The 67-year-old man shot at least two flares in an attempt to get passing boats to take notice of him.

The attempt appeared to work, according to Kenneth Wiese, a spokesperson for the US Coast Guard’s south-west district. Wiese said people onboard two separate vessels contacted the National Park Service to say they suspected someone was marooned on Santa Rosa Island, part of Channel Islands national park off the southern California coast.

The Coast Guard sent a helicopter that was already in flight to retrieve the man, who had spent the night on the island. The man had etched the letters “SOS” into the charred ground, according to images posted to Instagram by the Coast Guard. Officials took him to a hospital in nearby Camarillo. He did not appear to have been injured.

“We do know that he launched some flares to try to get some attention,” Wiese said. “It paid off for him. We were able to get him out of there.”

But the flares may have set off a wildfire along the southern coast of the 53,000-acre island. Wiese said he could not confirm the cause of the fire, but said the National Park Service (NPS) was carrying out an investigation. The NPS did not immediately respond to a request for comment.

The NPS posted a notice on Sunday that Santa Rosa Island was closed to visitors while firefighters attempted to control the fire. The agency evacuated staff on Sunday, according to the Mercury News.

The fire has reportedly destroyed two structures: Johnson’s Lee Equipment Shed and Wreck Line Camp Cabin.

The Channel Islands boast high levels of biodiversity that has led some to describe them as the “Galapagos of California”. But Santa Rosa Island’s ecology has been compromised by more than a century of uncontrolled grazing by livestock and non-native ungulates set loose there for hunting. Both the livestock and non-native wildlife were removed more than a decade ago, allowing native plants to rebound.

Six native plants grow exclusively on Santa Rosa Island, according to San Francisco Gate. The NPS is also hoping that firefighters can shield a rare area of Torrey pines from the blaze, the outlet reported.