A Whitehorse RCMP officer has been reassigned and outside investigators called in after a video showing a violent arrest went viral. The video was shot on Sunday and posted to Facebook soon after. It has been viewed more than half a million times, and shared more than 11,000 times.

The short video appears to have been shot in someone's kitchen. An RCMP officer holds a man on the ground while several angry voices are heard off-camera. It is not clear why the man is being arrested. No other people are seen in the video.

"I'm doing nothing," the man says while he's held on the ground. "Why are you hitting me?" he asks, before the officer appears to punch him in the head. The officer then forces the man onto his stomach and handcuffs him.

Yukon RCMP say the video warrants further investigation. In a statement released Tuesday, the police force says it has a duty to account to the public for its actions, including the use of force. But police say it's too soon to make an informed judgement about this case.

"Social media is a great tool, but sometimes it doesn't give you the whole story," says Whitehorse RCMP Insp. Archie Thompson. "It gives you part of the story."

RCMP say the Alberta Serious Incident Response Team (ASIRT) has been called in to conduct a criminal investigation.

Thompson says the officer shown in the video has not been charged, but the nature of the incident warrants a criminal investigation. In the meantime, the officer has been reassigned to administrative functions. Neither the officer's name nor the name of the man arrested in the video have been released by police.

Yukon RCMP say they will limit what they publicly say about the incident, to "avoid influencing the investigation or any future processes that may result."

It's not clear how long ASIRT's investigation may take.