ORONO – About 280 students were evacuated on Wednesday night from their University of Maine dormitory after a small chemical spill.

A student living in Knox Hall had muriatic acid, a corrosive substance typically used to clean concrete in outdoor settings, that he was intending to use for a class project, UM Spokesman Joe Carr said Thursday.

“It was in a plastic container that somehow became pierced with a small hole,” Carr said.

The spill occurred at about 10 p.m. and was not intentional, Carr said.

The chemical engineering student reported the spill to a resident assistant, who in turn called UM Public Safety.

About a cup of the substance leaked onto the hallway carpet before fire crews arrived.

The building was evacuated, and Orono and Old Town fire departments, as well as the Orono hazardous-materials response team, responded to the incident.

“They used an agent to neutralize the spill and removed the carpet,” Carr said.

Students were kept out of the building for about two hours and were allowed to return back to the dorm rooms shortly after midnight, according to Carr.

The caustic acid didn’t come in contact with anyone and no one was injured.