Pittsburgh Fire responded to a report of a house fire in the 7100 block of Idlewild Street around 9:30 p.m.
Firefighters came upon a vacant home fully involved. The fire eventually spread to a free standing neighboring home.
The fire, which went to three alarms, was contained in about 45 minutes. No one was injured.
The vacant home sustained heavy damage. The occupied neighboring home sustained substantial damage.
The Fire Investigation Unit, made up of investigators from Pittsburgh Fire and detectives from Pittsburgh Police, are investigating the cause of the fire.