PROVIDENCE, Rhode Island – It began shortly after 4pm, when a masked man burst into a lecture hall at Brown University with a rifle, yelled something incomprehensible, and began spraying bullets at the 60 or so

.

Some students were able to escape through the side doors of the hall. Others could only hide, ducking under chairs and behind desks. Two were killed, and nine wounded.

Mr Joseph Oduro, a 21-year-old senior and teaching assistant who was leading the study session, said he took cover behind a desk with about 20 others.

“The students in the middle were impacted the most,” he said. “Many of them were lying there, and they were not moving.”

Twelve hours after the shooting began, US marshals and local officers detained a person of interest at a hotel in Coventry, Rhode Island, about 32km south of campus. That person

was released without being charged

, the authorities announced in a news conference late on Dec 14.

The search for the shooter was continuing, the authorities said, as they asked for the public’s help and said they would be searching for video footage from the neighbourhood near the shooting scene.