A shooter dressed in black killed at least two people and wounded eight others at Brown University on Saturday during final exams on the Ivy League campus, authorities said, as police searched for the suspect.

Officers were hunting through campus buildings and sifting through trash cans more than three hours after the shooting erupted.

The suspect was a male in dark clothing who was last seen leaving the building, said Timothy O’Hara, Deputy Chief of Police.

Mayor Brett Smiley said a shelter-in-place was in effect for the area and encouraged people living near the campus to stay inside and not to return home until it is lifted.

“We have all available resources” to find the suspect, Smiley said.

The eight wounded people were in critical but stable condition, the mayor said. He declined to say whether the victims were students.

University officials initially told students and staff that a suspect was in custody, before later saying that was not the case and that police were still searching for a suspect or suspects, according to alerts issued through Brown’s emergency notification system.

The mayor said a person preliminarily thought to be involved was detained but was later determined to have no involvement.

“We’re still getting information about what’s going on, but we’re just telling people to lock their doors and to stay vigilant,” said Providence Councilmember John Goncalves, whose ward includes the Brown campus. “As a Brown alum, someone who loves the Brown community and represents this area, I’m heartbroken. My heart goes out to all the family members and the folks who’ve been impacted.”

The shooting occurred near the Barus & Holley building, a seven-story complex that houses the university’s School of Engineering and physics department. According to the university’s website, the building includes more than 100 laboratories, dozens of classrooms and offices.

Engineering design exams were underway in the building when the shooting occurred.

Brown senior biochemistry student Alex Bruce was working on a final research project in his dorm directly across the street from the building when he heard sirens outside and received a text about an active shooter shortly after 4 p.m.

“I’m just in here shaking,” he said, watching through the window as a half-dozen armed officers in tactical gear surrounded his dorm. He said he feared for a friend who he thought was inside the engineering building at the time.

Students in a nearby lab hid under desks and turned off the lights after receiving an alert about the shooting, said Chiangheng Chien, a doctoral student in engineering who was about a block away from the scene.

Students were urged to shelter in place as police responded to the scene, and people were told to avoid the area. A police officer warned media to take cover in vehicles because the area was still an active scene.

President Donald Trump told reporters that he had been briefed on the shooting and “all we can do right now is pray for the victims.”

“It’s a shame,” he said in brief remarks at the White House.