Local authorities in Northeast Ohio were forced to evacuate about 75 residents and more than 20 homes for a few hours on Monday after hydrochloric acid leaked from an oilfield services (OFS) semitruck.

A rusty valve is thought to be the cause of the leak, authorities said. A passerby called authorities around 7:30 a.m. on Monday after a vapor plume was spotted. Firefighters responded and called in a hazardous materials team at Predator Trucking Co. on U.S. Route 422 in Girard, about five miles north of Youngstown. Part of the road was closed, but reopened later in the morning when the evacuation was lifted.

Ohio Environmental Protection Agency spokesman Anthony Chenault confirmed that the truck is owned by Texas-based ProFrac Services, which has operated in the Appalachian Basin for about two years. While authorities estimated that more than 2,000 gallons leaked from the truck, Chenault said regulators don’t expect to have an actual number until later this week. There were no injuries.

Chenault said firefighters and the hazardous materials team contained the release with sand dikes. An environmental contractor was still at the site cleaning the spill on Tuesday. He added that no odor or vapor escaped the property and said no liquid was released. There were no impacts to water.

The acid is used commonly during well stimulation. It’s highly corrosive and mixed with water to dissolve contaminants such as scale and rust to clear the well and help oil and natural gas flow.