Members of the force are said to have been put on edge by the killing of an officer on Saturday during a robbery.

The officer was the third killed on duty in the city in the last two years.

"On the surface it certainly does not look good in terms of the amount of force that was used," Police Commissioner Charles Ramsey admitted, after seeing the video.

"But we don't want to rush to judgement."

It was not clear what preceded the confrontation.

Attorney D Scott Perrine, who represents the three men seen in the video, called the police actions unjustified.