By Greg Argos

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PHILADELPHIA (CBS) — Authorities are investigating the cause of a deadly fire in Northeast Philadelphia Friday afternoon. One man was killed and three firefighters suffered minor injuries.

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The harrowing call for a house fire with an entrapment came just after 4 p.m. Dozens of firefighters battled the flames and smoke in the home on the 3200 block of Birch Road in the northeast, but the conditions inside were “very challenging,” Philadelphia Fire Department commissioner Adam Thiel said.

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A possible hoarding situation coupled with the blaze meant firefighters had to shift their method of attack.

“We always try to fight the fire from the inside out. The reality is, depending on the degree of damage, depending on the structure, we always have to pull people out,” Thiel said.

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And when the fire was placed under control an hour later, firefighters pulled out one man killed during the fire. A second person is still unaccounted for.

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“We’re not happy with the outcome here,” Thiel said.

“I’m sad about it,” one neighbor said, “my heart goes out to the family.”

Dozens of neighbors gathered to watch the response.

“I’ve never seen something like this before,” one young girl said.

Nearly everyone said the people living in the home kept to themselves, and neighbors are just glad the fire did not spread to either adjacent home.

Although the fire did not spread, there was significant damage to one of the homes next door to the blaze. The Red Cross says six family members of that home have been displaced.

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The injured firefighters are expected to make full recoveries.