Northwest Fire District officials said a brush fire burning in an alley spread to a mobile home, on Monday. It happened in the 2800 block of W. Palm Vista near River and La Cholla. Fire officials said downed power lines presented a challenge for firefighters while they put out the flames. Employees from Tucson Electric Power arrived on scene to make sure the area was safe so crews could continue their fire-fighting efforts. Crews used several hoses to prevent the flames from spreading to the interior of the home. The cause is under investigation.