The boys, who were 9 to 15 years old, were attacked on Tuesday in what amounted to one of the war's worst cases of mistaken killings by foreign-led forces. The victims included two sets of brothers. A 10th boy survived.
The NATO statement, which included an unusual personal apology by the commander of the NATO forces in Afghanistan, Gen. David H. Petraeus, said the boys had been misidentified as the attackers of a NATO base earlier in the day. News of the attack enraged Afghans and led to an anti-American demonstration on Wednesday in the village of Nanglam, where the boys where from. The only survivor, Hemad, 11, said his mother had told him to go out with other boys to collect firewood because "the weather is very cold now."
"We were almost done collecting the wood when suddenly we saw the helicopters come," said Hemad, who, like many Afghans, has only one name. "There were two of them. The helicopters hovered over us, scanned us and we saw a green flash from the helicopters. Then they flew back high up, and in a second round they hovered over us and started shooting. They fired a rocket which landed on a tree. The tree branches fell over me and shrapnel hit my right hand and my side."
The tree, Hemad said, saved his life by covering him so that he could not be seen by the helicopters, which. he said, "shot the boys one after another."
General Petraeus pledged to investigate the attack and to take disciplinary action if appropriate.
"We are deeply sorry for this tragedy and apologize to the members of the Afghan government, the people of Afghanistan and, most importantly, the surviving family members of those killed by our actions," he said. "These deaths should have never happened."
It was the third incident in two weeks in which the Afghan government has accused NATO of killing civilians. NATO strongly disputes one of those reports, but another -- the killing of an Afghan Army soldier and his family in Nangahar Province on Feb. 20 -- was also described as an accident.
The attack on the boys occurred high in the mountains outside Nanglam in the Pech Valley of Kunar Province. American troops are preparing to close their bases in the valley in the next several weeks, in part because their presence has vexed the villagers, who would prefer to be left alone. The area is poor, and the only major road was built to service Forward Operating Base Blessing, according to local residents.
A rocket attack on the base on Tuesday led to a helicopter search for the insurgents responsible, the NATO statement said. The base is surrounded by mountains and is the frequent target of Taliban fighters, who shoot down on it from the rocky heights.
The helicopters "returned fire at the assessed point of origin with indirect and aerial fire," the NATO statement said. "Regrettably there appears to have been an error in the handoff between identifying the location of the insurgents and the attack helicopters that carried out subsequent operations."
Villagers -- who heard the gunfire in the mountains and worried when the children did not return home -- went to look for them. The boys had been out since the morning, local people said.
"As soon as we heard about the attack on the village's children, all the village men rushed to the mountains to find out what really happened," said Ashabuddin, a shopkeeper from Manogai, a nearby village, whose nephew Khalid was among those killed.
"Finally we found the dead bodies. Some of the dead bodies were really badly chopped up by the rockets," he said. "The head of a child was missing. Others were missing limbs."
"We tried to find the body pieces and put them together. As it was getting late, we brought down the bodies in a rope bed. We buried them in the village's cemetery," Ashabuddin added. "The children were all from poor families; otherwise no one would send their sons up to the mountains despite the known threats from both insurgents and Americans."
Khalid, 14, was the only male in the family, Ashabuddin said. "He was studying in sixth grade of the orphanage school and working because his father died four years ago due to a long-term sickness. His father was a day laborer. He has 13 sisters and two mothers. He was the sole breadwinner of the family. I don't know what would happen to his family to his sisters and mothers. They are all female and poor."
President Hamid Karzai, who was in London for an official visit, condemned the attack "in the strongest terms possible."
Calling it a "ruthless." he questioned whether the Western goals of combating terrorism and securing Afghanistan could be achieved if civilians continued to die.
More than 200 people gathered in Nanglam on Wednesday to protest the boys' deaths, witnesses said. Waving white flags, they shouted "Death, death to America" and "Death to Obama and his colleagues and associates."