Three Canadian soldiers were killed by an improvised explosive device while on patrol in Afghanistan's Zhari district, Canadian military officials have confirmed.

Task force commander Brig.-Gen. Denis Thompson made the announcement from Kandahar Thursday, adding that a fourth soldier was seriously injured by the blast.

The soldiers that were killed have been identified as Sgt. Shawn Eades, 33, Cpl. Dustin Roy Robert Joseph Wasden and Sapper Stephan John Stock.

The three soldiers were combat engineers with 12 Field Squadron, 1 Combat Engineer Regiment based in Edmonton, and were attached to the Second Battalion Princess Patricia's Canadian Light Infantry Battle Group.

The Canadian deaths come on top of an already deadly week for NATO forces in Afghanistan. 10 French soldiers and three Polish soldiers died while fighting militants this week.

But Thompson said that the attacks should not be seen as indicative that the Taliban is increasing in strength.

"What I'd say is that they're much more aggressive this fighting season than they've been in the past," Canada's top soldier in Afghanistan said.

But a retired Canadian general calls the Taliban's strength "disturbing."

"Open reports are now saying there are up to 8,000 foreign fighters across the border in Pakistan at 150 camps - that's very disturbing," retired maj.-gen. Lewis MacKenzie said. "In the last couple of years their numbers have grown and we haven't."

Chief of Defence Staff Gen. Walter Natynczyk called the deaths another example of how the security situation has worsened where the Canadians are stationed.

"The situation in the theatre has deteriorated over the summer and this is another reflection of that," Natynczyk told The Canadian Press in a telephone interview from Iqaluit, Nunavut.

The attack

The massive roadside bomb exploded while the soldiers were travelling to a site to do reconnaissance for a future mission.

The device detonated near the soldiers' vehicle at approximately 10:30 a.m. local time Wednesday, Thompson said.

"Afghan national police and Canadian Forces responded to the scene and medical evacuation was requested," he said.

"All four soldiers were evacuated to Kandahar Air Field. Sadly, three of the soldiers were confirmed dead by medical authorities."

Thompson said that the injured soldier was in "serious, but stable, condition."

"They were a well-trained, highly motivated crew that believed in the mission," said Thompson.

"As combat engineers they were proud, resourceful and armed with the technical knowledge that they generally used to assist the mission in helping the people of Kandahar province."

Prime Minister Stephen Harper issued a statement Thursday saying, "These three soldiers were exceptional Canadians who made a selfless choice to serve their nation."

"Their sacrifice will not be forgotten. We will honour their sacrifice by continuing on with this vital mission."

Soldiers' families release statements

Eades was married and had two daughters, Breanna, 7, and Nyia, 4. He was originally from Hamilton, Ont. and joined the cadets at 12, the military at 18.

"He was a strong leader who was highly respected by those around him," his widow, Lisa Schamehorn, said in a statement. "He died doing what he loved -- being a soldier."

"He believed in what he was doing and he knew he was making a difference for the people (in Afghanistan.)

"We love him and we will miss him."

Eades was interviewed by CTV last year in Edmonton about the Afghanistan mission.

"The cost is high but hopefully the end result will be worth it," he said.

Eades was widely "respected by his subordinates, his peers and his superiors," Thompson said.

"He was a veteran soldier and this was his third tour in Afghanistan," he said. "He was a devoted father who liked to share stories of his children with his colleagues and friends."

Stock's parents and younger brother released a statement Thursday night saying, "Stephan was loved by so many people, his circle of friends stretch from coast to coast and his family both here and in Ireland."

"He wanted his friends to have no fear for him because he had no fear of the mission in Afghanistan. We truly believe that if he came home safe that he would request to return for another tour."

Several Saskatchewan media outlets have reported that Wasden was from the Spiritwood area, about 200 kilometres north of Saskatoon and that he had a wife and young daughter.

The deaths bring the total number of Canadian soldiers who have died during the Afghan mission to 93.