A preliminary investigation by fire officials showed a window air conditioning unit was to blame for a structure fire Tuesday afternoon in the city of Reading. 

The fire was reported around 2 p.m. and the Reading Community Fire Department arrived on the scene, two blocks from their station, within seconds to find flames quickly spreading throughout a living area of the home. 

An interior attack and mutual aid from the Camden Fire Department prevented flames from spreading to the second floor of the structure. 

Nobody was home when flames erupted from the air conditioning unit, officials said, and no injuries were reported.