The fire broke out at the Austin Manor apartment building on the 7000 block of Rising Sun Avenue.
The first reports of fire came in around 4:30 a.m. More than 100 people were evacuated. Several residents were reportedly trapped inside their apartments.
Additional ladder trucks were called in to help with rescue efforts.
At least 19 people, including children, are being treated at Aria Hospital-Frankford and Temple University Hospital. Three of the victims sustained serious injuries.
Injuries range from burns to smoke inhalation, to trauma from jumping from upper floor windows.
This same apartment complex was the scene of a 5-alarm fire back in October of 2001 when 100 people lost their homes. The source of that fire was a candle.
Fire officials have not yet determined the cause of Sunday's fire, but fire officials say residents told them a candle may behind Sunday's blaze, as well.
The apartment complex landlord is providing residents with a place to stay in nearby apartments. The Red Cross says they, too, have found a place to stay for displaced residents.
The Red Cross tells Action News if anyone needs help they can get help by calling 215 299-4889.
Fire officials have not yet determined the cause of Sunday's fire, but one idea is that it was caused by a candle