A senior Canadian diplomat has been killed by a suspected suicide bomber in the southern Afghan city of Kandahar.
A witness said the vehicle was blown onto its roof
A Canadian spokesman said Glyn Berry, 59, was the political director of a reconstruction team in Afghanistan.
Two bystanders were also killed in the attack near a busy bus station, while 13 people, including three Canadian soldiers, were injured.
Two of the troops - part of Nato's peacekeeping mission in Afghanistan - are said to be in critical condition.
A man claiming to speak for the ousted Taleban regime said they had carried out the bombing.
The wounded soldiers were identified as Private William Salikin, Corporal Jeffrey Bailey and Master Corporal Paul Franklin.
Canadian Prime Minister Paul Martin called the attack a "tragic incident".
"On behalf of all Canadians, I want to express my condolences to the family of the individual who was killed and our prayers and best wishes to the family of the deceased and to the families of the injured," he said.
The Canadian convoy was travelling to its base when it was attacked, police told the BBC.
Many of the victims were civilians waiting at a nearby bus station, police said.
A witness contacted by the BBC described seeing a car drive into the convoy and blow up, creating an explosion loud enough to shake the windows of nearby buildings.
"I saw some soldiers lying on the ground. There were a lot of civilians as well who were being taken in the stretchers," Abdullah Jan said.
A wrecked vehicle was seen lying upside down on the road.
A man claiming to speak for the Taleban, Qari Mohammad Yousuf, told the Associated Press news agency: "These attacks will continue for a long time. We have many more suicide attackers ready to go."
Nato is seeking to expand its 19,000-strong deployment from peacekeeping duties in the capital Kabul to the volatile south of the country.
The south and east have been the scene of intense violence which last year left more than 1,400 dead, making it the deadliest year since 2001.
Much of the violence has been blamed on remnants of the hardline Taleban movement, which governed Afghanistan until the US-led invasion four years ago.