It happened at the Mays Landing Village condominium complex on the 1500 block of John Adams Court.
The fire broke out just before 1 a.m.
Flames were visible on the first and second floors of one of the units.
It's not clear where the firefighter was trapped, but he is now free and was not seriously injured.
No other injuries were reported.
There was no immediate word on the cause of this fire.