Last March, a convoy of US Marines was driving along the main road in eastern Afghanistan between Jalalabad and the border with Pakistan when they were attacked by a suicide bomber. One Marine was wounded in the attack.
A preliminary US military investigation found the Marines responded by firing indiscriminately at cars and pedestrians, killing civilians, including children and elderly villagers.
The Marines reported they were under small-arms fire following the bombing, but the investigation found no evidence to confirm their testimony.
A US commander in eastern Afghanistan, Army Colonel John Nicholson, says he has expressed his condolences to Afghan families who lost loved ones during the incident.
"Today we met with the families of those victims, 19 dead and 50 injured, and we made official apologies on the part of the US government and on the part of the coalition."
The death and injury toll is one of the largest involving civilians since the war in Afghanistan began in 2001.
Afghan President Hamid Karzai has publicly complained about civilian casualties caused by NATO and US-led troops fighting Taleban militants, saying the deaths are unacceptable.
Colonel Nicholson, speaking to reporters at the Pentagon by videoconference from Afghanistan, read the apology he made to the families.
"I stand before you today deeply, deeply ashamed and terribly sorry that Americans have killed and wounded innocent Afghan people. We are filled with grief and sadness at the death of any Afghan, but the death and wounding of innocent Afghans, at the hand of Americans, is a stain on our honor and on the memory of the many Americans who have died defending Afghanistan and the Afghan people. This was a terrible, terrible mistake and my nation grieves with you for your loss and suffering. We humbly and respectfully ask for your forgiveness."
Colonel Nicholson says the military made condolence payments, about two-thousand dollars for each death, to the families.
He says events that lead to civilian casualties hurt the military's image with the Afghan population and have to be addressed in a forthright manner.
"Regrettably it does happen because this is war. But we go to great lengths to avoid civilian casualties. If they do occur, we go to great lengths to try and make it right with the people who have suffered because that is not what America stands for."The military's investigation is continuing and Marines in the unit involved in the incident have been withdrawn from Afghanistan.