NATRONA HEIGHTS (KDKA) – A fire marshal is investigating a “suspicious” fire at a building in Allegheny County.

A building that used to be an old business in Natrona Heights caught on fire before 3 p.m. Monday afternoon.

The fire was small and the building was vacant, so no one was hurt.

There’s no word what caused the fire, and the fire marshall is investigating due to the “suspicious” circumstances.

Stay with for the latest on this developing story.