Afghan President Hamid Karzai has expressed his shock after nine children died in a US bombing in Afghanistan.
The US sent in an A-10 "Warthog" after receiving intelligence
He said his government had sent a team of investigators to the scene and had also sent officials to ensure the victims' families were being helped.
Earlier the United Nations condemned the incident as "profoundly distressing " and called for a swift inquiry.
The US has admitted mistakenly killing the children on Saturday in a strike on a suspected "terrorist".
The Afghan president said US forces should ensure that future operations were better co-ordinated with the Afghan Government to ensure such incidents would not happen again.
Earlier special UN envoy Lakhdar Brahimi said that such incidents added to the sense of "insecurity and fear" in the country.
US military spokesman Major Christopher West said ground forces found the bodies of the children near that of the intended target after the strike on a house near the city of Ghazni.
A commission has been formed to investigate the incident, he said, adding that the US military regretted the loss of innocent life.
Major West said the suspect was killed in the strike. He was thought to be behind the murders of two foreign contractors working on a ring road.
Five more people working on reconstruction projects have been kidnapped in the past three days - two Indians, and two Turks and an Afghan working with them.
The kidnappers are not reported to have had any contact with the authorities.
Only one house was hit in the attack without damaging others in the area.
Acting on "extensive intelligence", Major West said, an A-10 "Warthog" - a heavily armoured plane - was called in and opened fire on the isolated rural site at about 1030 local time (0600 GMT) on Saturday.
The US military followed "stringent rules of engagement" to avoid harming innocent bystanders, Major West added.
Afghan Government sources said they believed the incident was a mistake - the children were apparently playing nearby when the attack took place.
The BBC's Crispin Thorold in Afghanistan says the attack was very targeted, but that intelligence was not as good as it should have been.
He says local people - who are already sceptical of the US presence in the region - feel considerable resentment and anger in the wake of the attack.
It took place in a town where there is strong support for the ousted hardline Islamic Taleban and the Hezb-e-Islami group, also fighting the coalition.
Saturday's bombing is the latest in a series of attacks by US-led forces which have resulted in the deaths of dozens of Afghan civilians since the start of the campaign against the Taleban and al-Qaeda in October 2001.
"We have seen this before, so it's not as if we were speaking without experience," said UN spokesman Manoel de Alemeida e Silva.
Dec 2001: 65 killed in bombing of convoy of tribal elders
April 2002: Four Canadian soldiers killed
July 2002: 48 killed when bomb hits wedding party
April 2003: 11 killed by bomb in village of Shkin
Dec 2003: Nine children killed by bomb near Ghazni
*Mistakes accepted by US
Afghan officials said in September eight nomads were among 10 people killed when US forces bombed targets in a massive offensive against suspected militants.
The US military is investigating that attack after initially denying any civilians were killed.
In July last year, American forces killed at least 48 civilians when a stray bomb hit a civilian area in the southern province of Uruzgan.
Twenty-five of the dead were from a single family attending a wedding.
Although in many areas Afghans welcome the presence of American troops and other foreigners, there is hostility in some southern and eastern parts, our correspondent says.