Canadian soldiers were back patrolling the streets of Afghanistan's capital city Thursday night, just hours after two of their colleagues were killed in what appeared to be a landmine blast.

"I told them that the mission will continue," said Maj.-Gen. Andrew Leslie, the commander of Canada's 1,950-member peacekeeping contingent in the country.

"We will continue to protect the Afghan transitional authority, and the good citizens of Kabul."

Sgt. Robert Alan Short, 42, of Fredericton and Cpl. Robbie Christopher Beerenfenger, 29, of Ottawa died in the explosion. The injured soldiers are Master Cpl. Jason Cory Hamilton, 33, of Regina; Cpl. Cameron Lee Laidlaw, 25, of Oromocto, New Brunswick; and Cpl. Thomas Stirling, 23, of Assiniboia, Sask.

All five soldiers were members of the Royal Canadian Regiment, 3rd Battalion, based in Petawawa, Ont.

The road had been "cleared" by military engineers 24 hours earlier, according to the chief of defence staff, Gen. Ray Henault. Investigators are not sure if a new landmine was laid or if one had been missed by earlier teams.

There's no evidence it was a rocket blast, officials said, but they haven't ruled out anything. The explosive device appeared to have been detonated when the jeep drove over it around 1:45 p.m. local time, they told reporters at a news conference in Ottawa Thursday afternoon.

The two jeeps had extra armour beneath them, said Leslie. The soldiers were all wearing special protective gear. The explosion was so large, the right side of the first jeep was ripped away.

'If it weren't dangerous, they wouldn't need us'

Within hours of the tragedy, Leslie told more than 1,500 Canadian soldiers at the base in Afghanistan to remain sharp, and to honour the dead and injured by remaining professional. By nightfall, patrols had resumed.

"I told them that the mission will continue. We will continue to protect the Afghan transitional authority, and the good citizens of Kabul," the major-general said.

"This is a dangerous but worthwhile mission in a dangerous area. But if it weren't dangerous, they wouldn't need us," Leslie said.

"The Taliban and al-Qaeda want us to retreat to our camps or run away. And neither, of course, is an option for our soldiers."

Ottawa has about 1,800 soldiers stationed with a 31-country force of 5,500 in Kabul. The Canadians left for Afghanistan in August.

Canada is one of the largest contributors to the Kabul force.

NATO took over control of the force in August. ISAF currently focuses on Kabul, but the alliance is considering expanding its mandate to regions outside the capital.

The still-confidential plans could have as many as 10,000 troops added to the force, which would spread out to major provincial cities.

Prime Minister Jean Chrtien expressed deep sympathy on behalf of all Canadians in a statement Thursday.

Four Canadian soldiers died last year in Afghanistan when a U.S. fighter jet mistakenly bombed their position during a training exercise near Kandahar.

About 11,500 U.S.-led coalition troops remain in Afghanistan hunting down Taliban and al-Qaeda fighters.