Tier Parking Garage/Morgan Washington Center and Redevelopment Authority. Butler Eagle File Photo

Butler police are trying to determine who hung a large banner with a message against hydraulic fracturing on a city-owned parking garage during the weekend.

The banner saying “Fracking harms families. Reparations now!” was discovered and taken down Sunday, police said.

The garage wasn’t damaged and remains open, Jim Chiprean, the city’s parking manager, said Monday.

Police said the incident is under investigation.

Hydraulic fracturing, or fracking, is used in natural gas drilling to fracture underground rock formations to release gas. The process is controversial due to its use of carcinogenic chemicals.