SANTA CLARITA (CBSLA.com) — Some 3,300 firefighters from local, state and federal agencies have been working around the clock battling the massive Sand Fire that has scorched more than 35,000 acres in the Santa Clarita Valley since Friday.

They have been working 12-hour shifts in the sweltering heat for the past four days, trying to keep the flames away from homes and businesses.

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Using flares to set controlled burns or back fires is one way of keeping the flames from spreading. “They don’t actually have to walk up and physically put the fire on the ground. They’re actually able to do it from a distance. So they shoot that up into an area that is strategic,” Chris Reade of the Los Angeles Fire Department said.

CBS2/KCAL9’s Rachel Kim caught up with some members of the crew Monday as they returned from the front lines to eat and rest before going back.

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“We have some extremely high temperatures over 100 degrees. The fire behavior has been extreme, and the fire has been moving so fast that it’s hard to get out in front of it,” said Jayson Smith of the U.S. Forest Service.

“The hardest thing was staying awake because our whole crew had been on three days prior. This is our fourth day, and we got a little bit of sleep today, which was nice,” Dan Hagstrom of the Carpinteria Fire Department.

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Even though their job is tough and strenuous, the firefighters said they all love what they do.