Allegheny County dispatchers say the call for the fire came in at 6:58 p.m. on Saturday.
The fire alarm was triggered by a small stack of papers that were on fire that was quickly extinguished, officials say.
A large amount of smoke accumulated because the fire started in the basement.
“In this case, we were going down, which is a uniquely complicated scenario because when you get into a sub-basement it almost becomes like a maze and there’s nowhere for the smoke to go,” said City of Pittsburgh Assistant Fire Chief Brian Kokkila.
Firefighters had to remain on the scene after the fire was out to work to clear smoke from the building and tunnels.
The fire restoration company was also called to the scene.
There were no injuries.
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