Pittsburgh Police responded to a 9-1-1 call on the 2800 block of Centre Avenue around 9:45 p.m.
Responding Zone 2, officers located a child with a gunshot graze to the head. A second victim suffered a gunshot wound to the thumb.
Both were struck by gunfire after a dispute inside the apartment.
Medics transported both victims to a local hospital in stable condition.
SWAT and negotiators responded for an armed suspect possibly inside.
A K-9 officer and SWAT conducted a search of the building. Police found a weapon inside, but no suspect.
Residents were allowed to return inside the apartment around 11:15 p.m.
Police detained one individual and the investigation is ongoing.