( 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 . Grand jury to mull Ferguson case . 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 . A CNN crew also saw the officer point his weapon at those around him as he cursed , shouted and threatened people by saying he 'd kill them unless they stayed away . Complete coverage of Ferguson shooting and protests . 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 . This is not the first time unarmed protesters in Ferguson have accused police of pointing guns at them . CNN staffers have seen some such incidents first-hand that were n't caught on tape . Antonio French , a St. Louis city alderman who has been a fixture at the demonstrations , said he is not surprised by the video given what he 's seen the past two weeks . What is different -- in a good way , from his perspective -- is that authorities responded promptly in disciplining one of their own . `` In this case , we did see something happen to that officer immediately , '' French told CNN 's Anderson Cooper . `` And that sends a strong message that at least the folks at the top are getting it . '' Neil Bruntrager -- general counsel for the St. Louis Police Officers Association , though he does n't represent this specific accused officer -- conceded in an appearance on CNN that these kinds of things are probably happening in Ferguson , though he characterized them as `` isolated incidents . '' He defended the officers on the front lines of the protests , saying they have shown `` admirable restraint '' -- a view that 's not shared by some activists -- despite being persistently egged on . `` You 're asking them to stand there and stare into the faces of people who are spitting on them , who are yelling at them , who are screaming at them , ... who are touching them , '' Bruntrager told CNN 's Erin Burnett . `` You 're saying : Just take it . And ... by and large , they do . '' Sometimes -- as in this particular cases , the lawyer conceded -- a police officer may act improperly . If they do , Bruntrager claimed that it is `` a fatigue issue , '' not `` a training issue , '' related to the psychological wear on being on the streets of Ferguson day after day . `` What happens in a situation like this is that a person is human , they respond , and that 's what you saw ( on the video ) , '' Bruntrager said . `` It 's unfortunate , it 's unpleasant , but it 's a human response . '' The man in charge of maintaining security in Ferguson , Missouri State Highway Patrol Capt . Ron Johnson , considers this officer 's actions an affront to all those who have doing things the right way . Talking to CNN 's Don Lemon about the video , Johnson said , `` I was disturbed by it , I was bothered by it , and I was disrespected by it . '' Column defending cops in Ferguson spurs online fury . Magazine : The Aftermath in Ferguson . Read more about the flash point in the Heartland at CNN.com/US .
NEW : Official in charge of security : `` Disturbing '' incident disrespects other officers . NEW : Protester lauds the disciplining of the officer , says it sends a `` strong message '' A Missouri police officer `` relieved of duty '' after pointing rifle , threatening protester 's life . Police union lawyer : Incident is `` unfortunate , '' officers are tired and `` human ''