The Mayerthorpe tragedy occurred on March 3, 2005 on the property of James Roszko, approximately north of Rochfort Bridge near the Town of Mayerthorpe in the Canadian province of Alberta. With a Heckler & Koch 91, Roszko shot and killed Royal Canadian Mounted Police constables: Anthony Gordon, Lionide Johnston, Brock Myrol and Peter Schiemann. The incident occurred as the officers were executing a property seizure on the farm. This was the worst one-day loss of life for the RCMP and the worst multiple-officer killing in modern Canadian history.