DUQUESNE (KDKA) — Authorities are investigating the cause of an overnight fire at a vacant duplex in Duquesne that forced the family living in the home next door to evacuate.

The fast-moving, three-alarm blaze broke out before 2 a.m. on South 5th Street.

Officials say the structure was boarded up and sealed, but the utilities were still on inside.

“We had heavy fire coming out of all sides of the building,” said Andrew Fedor, the assistant fire chief in Duquesne. “Initial crew came on scene, did a good knock down. We had a couple exposure problems. They did a good job saving all the exposures.”

A family of five evacuated a neighboring home as a precaution while crews put out the blaze. They have since been allowed to go back inside, but the home did sustain some damage.

“Two police officers came knocking on the door and told us to get out. We thought someone was breaking into our house,” said George Taylor, a neighbor. “Like 11:30 we went to bed, and they woke us up about 1:30, 2 for us to get out because a duplex was on fire.”

According to preliminary reports, officials say the blaze could have started on the back porch of the vacant structure, but nothing official has been determined. The roof of the porch was destroyed along with some furniture that was being stored there.

Over concerns from neighbors, investigators are looking into whether smokers from a neighboring bar could have sparked the fire.

There were no injuries reported and the duplex is believed to be stable.

The fire marshal continues to investigate the cause.

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