The suspect was a man in dark clothing who was last seen leaving the engineering building where the attack happened
At least two people have been killed and nine wounded at Brown University during final exams on the United States university campus.
Police continue to search for suspect, a gunman dressed in black, Associated Press reports say.
University president Christina Paxson said she was told that 10 people who were shot on December 13 were students at the university in Providence, Rhode Island. Another person was injured by fragments from the shooting, but it was not clear if that victim was a student, she said.
Officers scattered across the campus and into an affluent neighbourhood filled with historic and stately brick homes, searching academic buildings, backyards and porches late into the night after the shooting erupted in the afternoon.
The suspect was a man in dark clothing who was last seen leaving the engineering building where the attack happened, said Timothy O’Hara, deputy chief of Providence police.
Security footage showed the suspect walking away from the building, but his face was not visible. Some witnesses reported that the man, who could be in his 30s, may have been wearing a camouflage mask, Mr O’Hara said.
Investigators were not yet sure how the gunman got inside the first-floor classroom where he opened fire. Outer doors of the building were unlocked, but rooms being used for final exams required badge access, Providence’s mayor said.
Authorities believe the suspect used a handgun, according to a law enforcement official who was not authorised to discuss an ongoing investigation and spoke on condition of anonymity.
“The unthinkable has happened,” said Democratic Rhode Island Governor Dan McKee, who vowed that all resources were being deployed to catch the suspect.
Mayor Brett Smiley said a shelter-in-place order remained in effect and encouraged people living near the campus to stay inside or not return home until it is lifted. Streets that normally bustle with activity on weekends were eerily quiet.
“The Brown community’s heart is breaking, and Providence’s heart is breaking along with it,” Mr Smiley said.
Nine people with gunshot wounds were taken to Rhode Island Hospital, where one was in critical condition, said Kelly Brennan, a spokesperson for the hospital. Six required intensive care but were not getting worse, and two were stable, she said.
University officials initially told students and staff that a suspect was in custody, but later said that was not the case.
The mayor said a person preliminarily thought to be involved was detained but was later determined to have no involvement.
Nearly five hours after the shooting, officers in tactical gear led students out of some campus buildings and into a fitness centre.
The shooting occurred in the Barus and Holley building, a seven-storey complex that houses the School of Engineering and the 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 there when the shooting occurred.
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.
Mari Camara, a junior from New York City, was coming out of the library and rushed inside a taqueria to seek shelter. She spent more than three hours there, texting friends while police searched the campus.
“Everyone is the same as me, shocked and terrified that something like this happened,” she said.
Brown, the seventh-oldest higher education institution in the US, is one of the nation’s most prestigious colleges, with roughly 7,300 undergraduates and more than 3,000 graduate students.
President Donald Trump told reporters that he had been briefed and “all we can do right now is pray for the victims”.
Rhode Island has some of the strictest gun laws in the US.
Last spring, the Democratic-controlled Legislature passed an assault weapon ban that will prohibit the sale and manufacturing of certain high-powered firearms, but not their possession, starting next July.
