James Roszko murders four Royal Canadian Mounted Police constables during a drug bust at his property in Rochfort Bridge, Alberta, then commits suicide. This is the deadliest peace-time incident for the RCMP since 1885 and the North-West Rebellion.

The Mayerthorpe tragedy occurred on March 3, 2005, on the farm of James Roszko, approximately 11 km (6.8 mi) north of Rochfort Bridge near the town of Mayerthorpe in the Canadian province of Alberta.

The Royal Canadian Mounted Police is the national police service of Canada. The RCMP is an agency of the Government of Canada; it also provides police services under contract to 11 provinces and territories, over 150 municipalities, and 600 Indigenous communities. The RCMP is commonly known as the Mounties in English.

Rochfort Bridge is a hamlet in Alberta, Canada within Lac Ste. Anne County. It is located approximately 105 kilometres (65 mi) northwest of Edmonton and 8 kilometres (5.0 mi) east of Mayerthorpe. Rochfort Bridge is named for Cooper (Cowper) Rochfort, who with his associate, Percy Michaelson, homesteaded on the Paddle River at the point where the old trail from Lac Ste. Anne to the MacLeod River crossed the Paddle River.

The North-West Rebellion, was an armed rebellion of Métis under Louis Riel and an associated uprising of Cree and Assiniboine mostly in the District of Saskatchewan, against the Canadian government. Important events included the Frog Lake incident, and the capture of Batoche.