A protester assaulted a group of New York Police Department cops, including the highest-ranking uniformed member of the department, on Wednesday during a demonstration on the Brooklyn Bridge, according to police and footage of the attack.

The NYPD announced in a tweet around 12:30 p.m. that at least three officers were hurt by someone swinging a long object at the officers while they were placing someone under arrest on the opposite side of one of the bridge’s fences.

A police department spokesperson said the Chief of Department, Terence Monahan, is the other white-shirt member of the department seen in the video with the group at the time of the attack and suffered a non-life-threatening hand injury.

The video shows someone from the group along the bridge approaching the edge of the fence, leaning over and whacking the officers huddled against the barrier.

Three officers suffered serious injuries, the tweet states.

Monahan was one of the NYPD members lauded for taking a knee with protesters during a demonstration in the city on June 1.

It was not immediately clear if the video showed the only incident of violence or if others had occurred off-camera.