The blaze broke out in the chimney of a home on the first block of Oak Ridge Road in Washington Township around 12:20 a.m., police said in a news release.
All occupants had safely escaped the home as officers arrived, police said. No injuries were reported.
The fire remains under investigation. Additional details were not released.
Assisting agencies include the Washington Township Fire Department, Borough Fire Department, Oxford Township Fire Department, Mansfield Township Fire Department, Hackettstown Fire Department, Washington Emergency Squad, Mansfield Township Emergency Squad, Warren County Communications Center and the Warren County Fire Marshall.
Scroll down to view more photos of the scene.
Click here to follow Daily Voice Highland Lakes-Vernon and receive free news updates.