Pittsburgh Fire responded to a rowhouse fire on 44th Street in Lawrenceville around 4:45 p.m.
The fire started in the second rowhouse of a four-house section on the 90 block of 44th Street. Flames spread to each adjoining unit.
The fire caused extensive damage to the first and second home, both of which were vacant. The third and fourth rowhouses, which were occupied, sustained some damage.
Firefighters contained the flames by 5:38 p.m.
No one was injured.
The Fire Investigation Unit, made up of investigators from Pittsburgh Fire and detectives from Pittsburgh Police, are investigating.