Flames broke out just before 9:00 p.m. inside the Fairhill Apartment, located at 2443 North 11th Street.
The fire started in an apartment on the 16th floor of the 18-story Philadelphia Housing Authority building.
Crews on the scene say it began as a mattress fire but the sprinkler system put it out.
A next door neighbor tells Action News that a woman lives there with two children and got out safely.
Crews think a water main break in the basement may have triggered something to cause the generator to shut off and the power to go out.
The power outage caused evacuations of more than 150 units but those residents have since been allowed to return home.