The incident happened in Portapique, a rural town in Nova Scotia, Canada, and the shootings took place in numerous locations.
Officials have said it is possible there are more victims who have yet to be discovered.
The gunman, identified as Garbriel Wortman, 51, was wearing a police uniform and drove a fake marked police car, but was not employed by Canadian police.
He is believed to have made and fitted dentures, but his high school year book reportedly alluded to his dream of being a police officer.
Heidi Stevenson, a Royal Canadian Mounted Constable, was among the victims. She leaves behind two children and her husband.
Authorities believe the gunman's first attack was targeted but he later fired at random.
Wortman died during a stand-off with police, with authorities saying officers discharged their firearms. His cause of death has not been officially confirmed.