ANTIOCH (CBS SF) — A one-alarm brush fire grew to 13 acres early Thursday morning, threatening to spread to boats moored at the Antioch marina before firefighters were able to contain the blaze, authorities said.

East Contra Costa County firefighters responded to the fire near 1 Marina Place at around 3 a.m. By 7 a.m., the crews were able to gain containment of the blaze and begin mop-up operations.

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Flames from the blaze were visible for miles in the predawn hours as the fire roared through brush that was tinder dry because of extreme drought conditions. Fortunately, overnight winds off the Delta in the area were relatively calm.

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Downed PG&E lines did slow the firefighters’ response as an amber cloud of sparks rained down on boats in the marina.

Firefighters were successful at halting the spread into the marina. The fire was apparently sparked in a homeless encampment, Contra Costa County Fire Protection District Capt. Tracie Dutter said.

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No injuries were reported. The cause of the fire was under investigation.