A police sergeant’s gun “accidentally” fired inside a Columbia University building where officers were removing pro-Palestinian protesters from the campus this week, the New York Police Department said on Friday.

The sergeant had broken the glass of a locked office on the first floor of the building and switched his firearm — a 9-millimeter handgun with a flashlight mounted on it — from his right hand to his left hand to reach through the broken glass to unlock the door from the inside, said Carlos Valdez, assistant chief of the Emergency Services Unit.

As he switched hands, the gun went off. The bullet traveled through the glass, hit a frame of a wall and landed on the floor, the police said.

“After the firearm discharged, the sergeant immediately assessed his team and ensured that nobody was injured,” Chief Valdez said. “The team gained access to the office and found that nobody was inside.”

All of the protesters had been moved to one area of the first floor, but the police did not know at the time whether anyone was inside of the locked office before they entered, officials said on Friday.

The unidentified officer, who Chief Valdez said was “very experienced” and had been a sergeant with the unit for eight years, will receive training and be re-evaluated, he said.

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