It happened around 8:30 p.m. at a vacant home on the 700 block of Southard Street.
Chopper 6 was over the scene as flames were shooting through the roof of the two-and-one-half-story structure.
Chopper 6 over massive 3-alarm fire in Trenton
The deputy fire chief tells Action News it appears to have been a "hoarder" house, which made it nearly impossible for firefighters to get inside.
It took crews about two hours to get the fire under control.
No injuries have been reported.
The cause of the fire remains under investigation.