PROVIDENCE, R.I. — A manhunt was under way Saturday after two students were killed and nine other people injured in a mass shooting at Brown University, prompting a campus-wide lockdown as police searched for a suspect who remains at large.

The gunman opened fire in a classroom at around 4 p.m. local time in the Barus and Holley building, part of the university’s engineering school, where exams were being held. Authorities said the suspect fled the scene and had not been apprehended hours later.

Rhode Island Hospital officials said most of the injured were in “critical but stable” condition. The identities of those killed and wounded have not been released.

“This is a day that we hoped never would come to our community. It is deeply devastating for all of us,” Brown University President Christina Paxson said in a statement.

Providence police said the suspect is a male dressed in black and may have been wearing a mask. Surveillance footage showed him leaving the building after the attack, but his face could not be seen.

Police said they have not recovered the weapon and do not know the shooter’s motive or whether he has any connection to the university.

“We’re utilising every resource possible to find this suspect,” Providence Deputy Police Chief Tim O’Hara said, adding that additional armed officers had been deployed across the area.

Students and staff in parts of the campus were ordered to shelter in place, with police escorting people out of buildings once they were cleared. University officials said non-residential buildings would be searched as a precaution.

An economics professor told local media the shooting occurred during a review session led by a teaching assistant. She said students scrambled for cover as shots were fired.

Exams scheduled for Saturday were canceled, university officials said.

President Donald Trump described the shooting as “a terrible thing” and said prayers were with the victims. Rhode Island Governor Dan McKee called the incident an “unthinkable tragedy” for the state’s capital city.

Brown University, an Ivy League institution founded in 1764, has more than 11,000 students and is located in Providence, about 50 miles south of Boston.

The attack brought the number of mass shootings in the United States this year to 389, according to the Gun Violence Archive, which defines a mass shooting as one in which four or more people are killed or injured, excluding the attacker. — Agencies