KABUL, Afghanistan (AP):

A single-file line of schoolchildren walked past a military checkpoint yesterday as a bomb-loaded truck veered towards them and exploded, ending the lives of 14 young Afghans in a heartbreaking flash captured by a United States military security camera.

The video shows an SUV slowly weaving through sandbag barriers at a military checkpoint just as a line of schoolchildren, most wearing white caps, come into view. They walk along a pathway between the street and a wall, several of them pausing for a few seconds in a group before moving forwards again. The vehicle moves towards the security camera while the children walk in the opposite direction, nearly passing the SUV when the footage ends in a fiery blast.

Photos of the bombing's aftermath showed bloodied textbooks lying on the ground beside small pairs of shoes. Afghan officials said the children were attending a final day of class for the year to find out whether they would move up to the next grade.

Eight- to 10-year-olds

Dr Abdul Rahman, a doctor at a hospital near the blast, said the children were aged eight to 10.

The US military said the attack in the eastern province of Khost killed 16 people, including 14 children, an Afghan soldier and another person - likely a private security guard that Afghan officials reported killed. The US said 58 people were wounded.

In an angry condemnation of the attack, President Hamid Karzai said those that carried it out "cannot escape the revenge of Afghans and God's punishment".

The United Nations mission in Afghanistan and the NATO-led force also strongly condemned the attack.

The blast went off near the entrance to a police and army post, said Yacoub Khan, the deputy police chief of Khost. US troops are also stationed inside the outpost, but no troops were wounded or killed in the attack.

US General David McKiernan, the top NATO commander in Afghanistan, said he believed the militant network run by warlord Siraj Haqqani was responsible for the attack.

"The brutality and disregard for human life by terrorists is sickening, as I continue to witness innocent men, women and children being killed and maimed in the pursuit of this pointless insurgency," McKiernan said in a statement.

Afghan officials offered a slightly lower death toll. Abdullah Fahim, spokesman for the Ministry of Health in Kabul, said eight people in total died and 51 were wounded. Khan said he believed that only five schoolchildren had died.

It was not possible to reconcile the differing death tolls, though the US military video seemed to support the likelihood of the higher toll.

Security issues

Khan said the attack came at a time when Pashtun tribal elders from Mandozai district were meeting inside the compound to discuss security issues. It was not immediately clear how many, if any, of those tribal leaders were wounded or killed. Khan said it was possible they were the target but that there was no way for him to know for sure.

The attack came on the last day of school for the year. Students had gathered in the classrooms to receive end-of-year certificates and learn if they had passed on to the next grade, Asif Nang, spokesman for the Ministry of Education, said.

A UN spokesman said the UN mission in Afghanistan was "appalled" at the suicide attack.

"The deaths of young children who were receiving their end-of-year education certificates are particularly galling," said Dan McNorton.

The blast in Khost province came only hours after a late-night rocket attack in Kabul on Saturday killed three teenage sisters. McNorton said that attack "also reminds us of the true impact this conflict has on those who play no part in it".