The home at 63 Red Maple Lane was fully engulfed when firefighters arrived on Monday afternoon.
"Upon our arrival we got a report that there may be a male subject inside the residence still," said Chief Kevin Dippolito, the Bristol Township Fire Marshal.
After further inspection on scene, firefighter found a 30-year-old man dead in the backyard with severe burns.
The unidentified man's girlfriend was on the scene but uninjured. She appeared visibly upset.
Joey Delaney lives across the street from the home.
"She was saying how he was sitting in the living room and he was pouring gasoline all over the living room. He set it on fire and he was just sitting in the chair when she came in. She said 'what are you doing, what are you doing,' and ran out of the house," said Delaney.
Police and the fire marshal's office have not yet determined cause but did say arson investigators are on scene.
Neighbors say there is a history of domestic problems at the home.
An autopsy on the body of the man found dead is planned for Tuesday.