Warning: The story and video below contain graphic language

(CNN) – An officer who pointed a semi-automatic assault rifle at a Ferguson, Missouri, protester and threatened to kill him — a tense episode caught on video and posted online — is off the job, at least for now.

The St. Louis County Police Department announced Wednesday that a police officer from St. Ann, Missouri, “has been relieved of duty and suspended indefinitely” over the incident.

Police threatening to kill a citizen takes on special significance given what protesters are loudly, passionately demanding: charges against Ferguson Police Officer Darren Wilson for the August 9 fatal shooting of Michael Brown, an unarmed African-American teen.

The county police department laid out its version of the more recent incident, which happened shortly before midnight Tuesday. This account jibed with video later posted to YouTube.

In the video, an officer can be seen walking around with his assault rifle raised, then pointing it in the direction of protesters.

“I’m going to f–king kill you,” he says. “Get back. Get back.”

The St. Louis County Police described the protester involved in what it deemed “a verbal exchange” to be “peaceful.”

Another man in the crowd then says out loud, “Did you threaten to kill him?”

The officer is asked for his name, to which he responds: “Go f–k yourself.”

Protesters proceed to mock the officer before he’s led away by another member of law enforcement.

The St. Louis County Police said that one of its sergeants “walked over and immediately took action, forcing the officer to lower the weapon and escorting him away from the area.”

“The unified command strongly feel these actions are inappropriate, and not indicative of the officers who have worked daily to keep the peace,” the police department said.

The county police referred media to the St. Ann Police Department for updates on the unnamed suspended officer’s status. Members of the law enforcement force charged with maintaining security have come from many communities, including St. Ann, which is just west of Ferguson.