MONESSEN, Pa. — (WPXI) – Two vacant buildings in Westmoreland County were damaged in an early morning fire. The fire started along Rostraver Street in Monessen just after 3:30 a.m. The Monessen Fire Department No. 1 said the structures were fully involved. One of the buildings collapsed, and another was damaged. Westmoreland County 911 officials say no one was hurt because of the fire. Fire crews remained in the area for around 6 hours. The cause of the fire remains under investigation.