The fire broke out just after 5 a.m. in the 3800 block of Bensalem Boulevard in Bensalem Township.
Firefighters arrived to find flames shooting though the roof of the two-story building.
Officials evacuated several people from neighboring apartments while crews worked to battle the blaze.
Bensalem Township fire officials are working to determine the cause of the blaze.
The Red Cross is assisting the displaced residents.