At least two people were killed and nine others were injured, some of them critically, in a Saturday afternoon shooting at Brown University in Providence, Rhode Island.
The shooter remains at large despite initial reports that a suspect had been taken into custody.
Law enforcement authorities released a video showing a "person of interest" in the shooting.
Providence Mayor Brett Smiley said the shooting occurred at the Barus & Holley building, which houses the university’s engineering and physics departments.
“The unthinkable has happened,” Rhode Island Gov. Daniel McKee said at a news conference.
Brown University President Christina Paxson said the two people who died were students.
US President Donald Trump told reporters he's been fully briefed about the deadly shooting.
"What a terrible thing it is. And all we can do right now is pray for the victims," he said.
A text message sent earlier by school officials warned students to "lock doors, silence phones and stay hidden until further notice," Fox News reported.
"Remember: RUN, if you are in the affected location, evacuate safely if you can; HIDE, if evacuation is not possible, take cover; FIGHT, as a last resort, take action to protect yourself," school officials wrote in the alert. "Stay tuned for further safety information."
As of 8:55 p.m. EST, the students were still not given the all-clear. Paxson wrote to students that "the suspect is still at large and the situation remains active. We know this is a source of tremendous fear and anxiety across our community right now. While DPS was at one point informed that there was an individual in custody, that person was determined not to be the shooting suspect after questioning. Therefore, we urge all members of our community to remain vigilant. We continue to be in lockdown, and it is imperative that all members of our community remain sheltered in place. This means keeping all doors locked and ensuring no movement across campus."