▶ Watch Video: Likely cause determined in deadly Philadelphia fire

A deadly Philadelphia rowhome fire most likely started when a Christmas tree was ingited by a lighter, authorities said Tuesday. They reached their conclusion after interviewing a 5-year-old who survived the fire and ruling out all other possible explanations, they said.

A search warrant issued last week showed that authorities were looking into the possibility that a 5-year-old was playing with a lighter when a nearby Christmas tree was ignited, according to the Associated Press. Authorities did not fully confirm this exact theory during Tuesday’s news conference, but they said they are “near certain” that the lighter and tree were the sources of the fire.

Investigators said they found no evidence that disproved the child’s account, but noted that, because of his age, they couldn’t prove he started the fire based solely on his testimony.

“We are left with the words of that 5-year-old child, that traumatized 5-year-old child, to help us understand how the lighter and the tree came together with tragic consequences,” fire commissioner Adam Thiel said Tuesday. “We are not going to get into details of the words of a 5-year-old.”

The child was one of only two survivors, and the only survivor from the second floor of the rowhome, where the fire started. Twelve people, including nine children, died in the fire last week. All of the victims were found in bedrooms on the third floor, Thiel said.

On Tuesday, the Philadelphia Department of Public Health’s Medical Examiner’s Office identified the victims as Dekwan Robinson, Destiny McDonald, Janiyah Roberts, J’Kwan Robinson, Natasha Wayne, Quientien Tate-McDonald, Quinsha White, Rosalee McDonald, Shaniece Wayne, Taniesha Robinson, Tiffany Robinson and Virginia Thomas, according to CBS Philly.

Authorities arrived quickly to the scene, but Thiel said Tuesday it was “not what you see on television.”

“There was zero visibility,” he said, noting that temperatures reached nearly 1,000 degrees Farenheit at the ceiling. “Toxic smoke filling the entire building. And it’s loud in a fire.”

Fire officials discovered a total of seven smoke detectors in the rowhome — three in a kitchen drawer, one in a bedroom drawer, one on the floor and one on a bedroom ceiling. All had their batteries removed and were inoperable.

One smoke detector in the basement did activate, but it was too late to alert the fire victims on other floors.

Philadelphia fire officials are again reminding people to have an escape plan in place in the event of a fire and double check their smoke detectors. They are also installing free smoke detectors throughout the city. Last year, they distributed 1,100 to city residents, according to CBS Philly.

Authorities said Tuesday the investigation will take months to complete.

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