By Cambi Brown

TUOLUMNE COUNTY (CBS13/AP) —The Rim Fire burning at Yosemite National Park is gaining strength, becoming the 13th-largest wildfire in California history.

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High winds and extremely dry conditions fueled the flames on Sunday, threatening thousands of homes.

The 149,780-acre blaze is larger than Chicago, destroyed at least 11 homes, and it’s threatening 4,500 homes and the Hetch Hetchy reservoir, the source of San Francisco’s drinking water. It was 15 percent contained on Monday morning, up 7 percent contained from the previous night.

“We don’t know which way it will go with the winds being unpredictable.”

If the fire continues its destruction this far west, thousands of homes will be threatened.

Mandatory evacuations have been issued throughout the week, but the Mariposa County Sheriff’s Department added one for Old Yosemite Road.

An evacuation warning has been issued for neighborhoods north of Bull Creek Road, Bondurant Mine Road, Texas Hill Road and Pampum Hill.

Strike teams are waiting nearby to protect homes, just in case this erratically moving fire takes a devastating turn.

Cal Fire cleared brush, trying to stay one step ahead of the fire.

“Slow the fire, stop the fire. It gives us a place to work from. Keep it out of the communities of Tuolumne.”

Their work on the ground is also helpful for crews in the air. It gives them a market for where to drop water and fire retardant.

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“They can see the line from up above”

Homeowners nearby are confident firefighters have everything under control.

“These firefighters are amazing and they’ll keep us protected.”

Thousands of people are watching their efforts, keeping a close eye on the looming smoke.

“Pretty impressive. It looks like a very coordinated effort and comforting to see and a little scary.”

Firefighters work around the clock, knowing every effort will at some point get this massive fire under control.

“It’s been a long day. A long past couple of days.”

Tuolumne County schools will be closed on Monday and Tuesday.

The Twain Hart Film Festival scheduled for Labor Day weekend is cancelled.

And for the first time in more than 30 years, the Strawberry Music Festival did not happen over the weekend.

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The Associated Press contributed to this report.