The bomber wore a vest packed with explosives and rode right up to the Nato gates on a bicycle, underscoring the insurgents' ability to strike deep inside the Afghan capital, ahead of the withdrawal of most foreign combat forces by the end of 2014.
Pieces of flesh and splattered blood lay on the street near the base, where the small bodies of children were lifted into ambulances. Scores of young children peddle trinkets and chewing gum around the foreign bases to earn a little cash.
Taliban spokesman Zabihullah Mujahid said the militant group had carried out the attack, but denied it had deployed a teenage bomber, saying instead he was a 28-year-old who targeted the Kabul offices of the US Central Intelligence Agency (CIA).
Nato's International Security Assistance Force condemned the use of children. "Forcing underage youth to do their dirty work again proves the insurgency's despicable tactics," said spokesman Brigadier General Gunter Katz.
Ministry of Interior spokesman Sediq Sediqqi said six civilians were killed in the attack, which took place just before noon, and five more wounded, including children.
Security was beefed up across the capital yesterday as celebrations were under way to commemorate the 11th anniversary of the death of Ahmad Shah Massoud, the hero of the 1980s' war against Soviet forces, and later a fierce opponent of the Taliban. Scores of dignitaries attended commemorations of Massoud's death in Kabul yesterday, which is a national public holiday in his honour.
Massoud was killed on September 9, 2001, by al-Qaeda militants posing as reporters. His assassination took place just days before the September 11 attacks on the United States. It was Massoud's Northern Alliance forces that joined with the United States to help rout the Taliban after America invaded Afghanistan a month later in the wake of the attacks.
Yesterday's bombing was the latest example of how militants are able to strike the most secure parts of the Afghan capital even after more than a decade of fighting Western forces with far superior firepower.
President Hamid Karzai blamed Afghan intelligence officials and Nato for failing to prevent the last major attack in Kabul in April, when a group of insurgents stormed several buildings in the diplomatic quarter, resulting in an 18-hour stand-off between security forces and militants.
Spokesman Sediqqi speculated on his Twitter feed that yesterday's attack may have been carried out by the Haqqanis network, the most experienced insurgents in Afghanistan.
On Friday, the US said it is designating the Haqqanis – blamed for a number of high-profile attacks on Western and Afghan targets in Kabul – a terrorist organisation.
Senior Haqqani commanders told reporters from an undisclosed location that the move showed the US was not sincere about peace efforts in Afghanistan and warned of more attacks on American forces in the country.