The fire began around 10:45 p.m. on December 26th inside a three story building.
A survivor said the blaze started when a kerosene heater spilled fuel, and it exploded as it was being moved outdoors.
Fire survivor Harris Murphy said those trapped in the basement blaze were part of the large Liberian enclave in southwest Philadelphia.
Three adults and four children died, including a 1-year-old boy, fire department Executive Chief Daniel Williams said.
Fire officials said six victims were found huddled together in the front of the basement, one of them cradling the baby. The seventh was found near the basement door.
The boy was later pronounced dead at Children's Hospital of Philadelphia.
The medical examiner said three of the children died of smoke inhalation and one adult died of smoke inhalation and burns. Four victims were identified as Henry W. Gbokoloi, 54, of Yeadon; 8-year-old Ramere Markese Wright-Dosso; 6-year-old Mariam Iyanya Dosso, and 1-year-old Zyhire Xzavier Wright-Teah. The three children all lived with their mother nearby.The Associated Press contributed to this report.