PHILADELPHIA – A portable heater burning either kerosene or gasoline in a home without smoke detectors sparked a blaze that killed seven people – four of them children – late Friday night in southwest Philadelphia, fire authorities and eyewitnesses said.

The fire erupted in a basement social room of a duplex on Elmwood Avenue where a group of adults was watching “The Bourne Ultimatum,” while the children slept on the floor, said Harris Murphy, one of the adults who escaped.

A female who lived at the property and was renovating the basement was pouring fuel into the heater when it exploded, said Murphy, a 35-year-old Liberian immigrant. He and the woman, as well as two other adults, escaped through the only exit, which was then blocked by the burning heater. The staircase to the rest of the house had been removed as part of the renovation, officials said.

Murphy said his brother, Henry Gbokoloi, 54, who perished in the blaze, tried to lead those who remained in the basement to a bathroom shower, which he thought would protect them from the flames.

But City Fire Commissioner Lloyd Ayers said six victims were found huddled together outside the bathroom toward the front of the basement. The seventh, a 2-year-old boy found near the exit, was taken to Children’s Hospital of Philadelphia, where he died.

“We feel real tough about that,” Ayers said.

Ayers said three others were hospitalized. Murphy was treated and released. The woman who poured the fuel and sparked the fire was treated and left the hospital, only to be re-hospitalized Saturday morning, he said. A third victim was in serious but stable condition at Chester Crozier Medical Center.

Ayers said the owner of the property was at work and not present when the fire erupted.

“This was a very, very catastrophic fire,” Ayers said.

Inza Dosso, 47, a Philadelphia parking attendant who emigrated from the Ivory Coast, said his two children, a daughter, Mariam, 7, and a son, Ramere, 8, were among the four children who perished.

Dosso said his children had been dropped off at the home by their mother, who was not present when the fire broke out. The couple are separated.

Dosso said the mother of his children was a friend of the woman who was renovating the property’s basement and was apparently hosting some type of holiday party. She was the mother of two other children who died in the blaze.

Ayers said the fire did not appear to have been set, but the cause was still under investigation. He said that kerosene heaters were found in several locations in the home and that an absence of smoke detectors appeared to have exacerbated the tragedy.