Although Acting US Ambassador to Afghanistan James Cunningham refrained from apologizing to the Afghan people and government, he offered his "deepest condolences" to the families of the victims, adding that US forces were "providing the highest level of care for those injured. We are still attempting to ascertain the facts."
The incident took place early Sunday in the district of Panjwaii in southern Kandahar Province when a US soldier opened fire on Afghan civilians inside their homes, killing at least 17 and injuring several others.
The US soldier has been reportedly detained following the assault.
Meanwhile, Afghan President Hamid Karzai has condemned the killings as “unforgiveable.”
“When Afghan people are killed deliberately by US forces, this action is murder and terror and an unforgivable action," Karzai said, adding that his people demand an explanation from the US government for the attacks.
Earlier, the NATO-led International Security Assistance Force (ISAF) in Afghanistan confirmed the “deeply regrettable incident.”
"I pledge to all the noble people of Afghanistan my commitment to a rapid and thorough investigation," Gen John R Allen, commander of the NATO-led forces said.
Civilian casualties in Afghanistan have been a major source of friction between President Hamid Karzai's government and the US.
The incident came in the wake of recent violent clashes in several provinces of the war-ravaged country over the Qur’an burning by the US-led forces, which left over 30 people, including six American soldiers, dead and around 180 others injured.
A UN report last month said more than 3,000 Afghan civilians died in 2011 alone.
The US-led invasion of Afghanistan was launched in 2001. The offensive removed the Taliban from power, but insecurity continues to rise across the country despite the presence of tens of thousands of US-led troops.