Officials are expected to start up an air attack on a brush fire that broke out in the mountains above Azusa on Monday and grew to 200 acres overnight, threatening about two dozen homes.

The Madre fire started about 6 p.m. Monday on the north side of California 39 in San Gabriel Canyon, the U.S. Forest Service said. 

Unstable winds that would not stop shifting were the first obstacles firefighters had to negotiate, but those died down about two hours after the blaze began.

Steep terrain was the next obstacle, and helicopters dropped firefighters behind the blaze to cut lines and keep the flames from advancing too quickly, said Los Angeles County Fire Department Inspector Keith Mora.

Helicopters kept making drops until about midnight, when it became too dark to fly, and Mora said they would resume operations Tuesday morning. 

As of late Monday night, the fire was listed at 190 acres. Early Tuesday morning, the U.S. Forest Service said the blaze had grown to 200 acres and was just 5% contained. 

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