Four Canadian police officers have been killed during a drug raid in rural Alberta, in the west of the country.
None of the officers killed had served longer than four years
Members of the Royal Canadian Mounted Police were shot dead while searching for cannabis on a small farm near the city of Edmonton.
Police said the owner of the farm also died in the incident, near the village of Rochfort Bridge.
Regional RCMP commander Bill Sweeney said Canada's police had not suffered such a tragedy for 120 years.
"The loss of four police officers is unprecedented in recent history in Canada," he said.
'Act of brutality'
"I'm told you have to go back to about 1885 in the RCMP history, during the north-west rebellion, to have a loss of this magnitude."
Prime Minister Paul Martin called it an act of "brutality" and offered his condolences to the families of the dead officers.
"It's devastating," he said.
The shoot-out was the worst single loss of police life for 120 years
Mr Martin was expected to ask for a minute's silence before opening his Liberal party's annual conference later on Friday.
Those killed have been named as Peter Schiemann, 25, Anthony Gordon, 28, Lionide Johnston, 32, and 29-year-old Brock Myrol.
Police said the four junior officers, none of whom had served more than four years, were searching for a suspected cannabis-growing operation and stolen property on a small rural farm on Thursday.
While they were there, farm owner James Roszko, 46, began firing at them with a high-powered rifle.
After reinforcements secured the scene, the officers were found dead in a large steel shed along with Mr Roszko, police said.
A government source told the Canadian Press news agency that Mr Roszko killed himself after shooting the officers.
Police in Alberta have been cracking down on illegal cannabis "grow-ops" that have sprung up across the province.
The shooting could also raise some awkward political questions for the government in Ottawa.
Mr Martin has announced plans to loosen laws on cannabis possession.
Critics have warned his plan could increase illegal cannabis production.
"The issue of grow-ops is not a ma-and-pa industry as we've been seeing for a number of years," RCMP Commissioner Giuliano Zaccardelli told the AP news agency.
"These are major serious threats to our society and they are major serious threats to the men and women on the frontline who have to deal with them."
Until now many Canadians have tolerated cannabis production as merely a minor nuisance, says the BBC's Ian Gunn in Vancouver.
This shooting during a cannabis raid is likely to reignite the debate and perhaps force the government to rethink its more liberal approach to the drug.