OKLAHOMA CITY - Fire officials are looking into the cause of a fire at a vacant house in southeast Oklahoma City, early Tuesday morning.

According to the fire department, at about 2:30 a.m., firefighters responded to the report of a fire at a two-story vacant house in the 200 block of S.E. 28th Street. The caller told fire officials that squatters stayed in the home. 

When firefighters arrived, they reported heavy fire conditions on the entire second floor of the home. Crews said they initially attacked the fire from the exterior using master streams from aerial apparatus and hand lines. 

Crews searched the entire structure, and nobody was found.  The fire was knocked down quickly, and firefighters extinguished the fire from inside the home. 

Fire Investigators were called to the scene, and the results of the investigation are still pending.