Military sources say a bomb that wounded two Canadian soldiers near Kandahar on Friday was carried by an 11-year-old boy and was detonated by remote control, killing the boy.
The two Canadian soldiers were not badly hurt, but the blast also struck two Afghan soldiers patrolling with them, one of whom later died.
The four soldiers were airlifted back to Kandahar Airfield for treatment after being attacked in the village of Nalgham, west of the city of Kandahar in southeastern Afghanistan.
The Canadians were well enough to walk into the trauma centre themselves. Both telephoned their families back home to let them know they were OK.
Few details of the attack were immediately available. The soldiers were on foot patrol at about 10 a.m. local time when the bomb exploded.
The Canadian Press quoted a military spokeswoman, Capt. Amber Bineau, as saying the boy is thought to have been wearing an explosive vest when he walked up to the patrol.
She condemned the attack as a "last ditch-attempt" by militants to disrupt the progress of Afghan and NATO forces in establishing security in the country.
"These types of attacks demonstrate a weakness in the insurgency and do not impede the resolve of those who work to make Kandahar province a safe and stable environment," she said in a statement.
There was no official confirmation of the bomber's age or how the bomb was triggered.
The attack came less than two weeks after a Canadian soldier was killed while on foot patrol in the Pashmul region, outside Kandahar City.
Cpl. Michael Starker, a Calgary paramedic, was shot and killed on May 6, while another Canadian was wounded, but is expected to recover.
In a separate attack not involving NATO forces Wednesday, a suicide bomber dressed in a burka struck a police station in the western province of Farah, killing 12 people and wounding 27 others.
Initial reports said the bomber was a woman, but the Taliban, which claimed responsibility for the attack, said it was carried out by a man named Mullah Khalid wearing the burka as a disguise.