RCMP say it happened on New Year's Day at the Russell Health Centre.
A 43-year-old man from Waywayseecappo First Nation went to the health centre for unspecified injuries he received in a snowmobile crash earlier in the day.
Mounties say a doctor and at least two nurses were treating the man when he became violent, assaulted them and then left the room.
Police say the man then assaulted a young girl and chased another child in the hospital, and uttered threats to other patients.
RCMP say the man was -- quote -- "extremely violent" with the officer, who had to use his Taser on the man to bring him under control.
Mounties say the man was not seriously injured from the Taser.
Police say the quick thinking and actions of the hospital staff prevented serious injury to the children, visitors, and other patients.
Substance abuse is considered a contributing factor.