(CNN) A group of people kicked a Baltimore police sergeant as he tried to arrest a man who'd spat in his face, authorities say.

The sergeant was conducting a business check just before midnight Friday when a person started arguing with him and spat on him, Police Commissioner Michael Harrison said in a statement Saturday. It's unclear what the argument or the check were about.

Video of the encounter that circulated online showed several others kicking the sergeant as he attempted to make an arrest, Harrison said.

"Based on our preliminary review of the incident, the sergeant did nothing to provoke the assault, and the sergeant should be commended for using the appropriate amount of force to apprehend his assailant," he said.

The commissioner added he was outraged by the incident.

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