Three police officers have been shot dead and two others injured in Canada's east coast province of New Brunswick, police said, as they conducted a manhunt for a man carrying a rifle and wearing camouflage clothes.

The Royal Canadian Mounted Police in New Brunswick said on its Twitter feed that three officers were dead and two others had sustained non-life threatening injuries on Wednesday. Police spokesman Paul Greene confirmed the deaths.

The RCMP said on Twitter that they were looking for 24-year-old Justin Bourque of Moncton. The police force tweeted an image of a suspect wearing military camouflage and wielding two guns.

Canadian police said on Wednesday night they believed the suspect was at large in a Moncton subdivision. They had a number of roads in the city blocked and traffic was backed up on major arteries across the city.

Moncton Mayor George LeBlanc urged all residents to pay strict attention to the RCMP warnings.

"The police and other emergency personnel are working under extremely difficult conditions and need our complete cooperation. Stay home, stay safe. If you cannot get home, seek out a friend or family and remain there until you are advised otherwise,'' LeBlanc said in a statement.

In an interview with CBC News, Greene said the officers were shot in the early evening after responding to reports of a man wearing camouflage clothing and carrying guns.

One witness said he saw the shooter in the distance on Wednesday evening, wearing a camouflage outfit and standing in the middle of the street with his gun pointed at police cars.

Danny Leblanc said he believed it was an RCMP officer he was looking at until he heard a burst of automatic gunfire coming from the man's gun.

Canadian Prime Minister Stephen Harper issued a statement saying the deaths of the officers would be honoured and remembered.

"This is a sad time for the people of Moncton, the people of New Brunswick and for Canada," he said.

A Facebook account allegedly belonging to Borque contained messages supporting the right to bear arms and posts critical of the police.

One picture posted on the account a few hours before news of the shootings broke condemns the 'militarisation' of the police forces around the world.

Moncton is a city of about 69,000 people about 1,177km east of Canada's capital, Ottawa.

Source: Al Jazeera and agencies