MOUNT OLIVER, Pa. —(WPXI)- Three juveniles were detained after shots were fired in Mount Oliver. Allegheny County dispatchers say officers were called to Hays Avenue at 1:58 p.m. The Mount Oliver Police Chief said he saw three juveniles shooting at a fourth when he arrived at Hays Avenue and Penn Avenue when he arrived. Police say the three shooters took off down Ormsby Avenue and went inside a house. Officers believe the house belongs to the sister of one of the shooters. SWAT units were called to the scene and the three shooters were detained. Police are still looking for the fourth person involved, the person who was being shot at. Allegheny County Sheriff’s Department vans were on Ormsby Avenue. Pittsburgh Police were also called for assistance. Officers are working on getting a search warrant so they can go inside the house on Ormsby Avenue. Medics were not called to the scene.