|The air base where the shooting took place is attached to Kabul International Airport [Reuters]
Eight foreign soldiers and a contractor have been killed in Afghanistan after an Afghan army officer opened fire at the air force headquarters at Kabul airport.
The Pentagon later confirmed that all those killed in Wednesday's incident were Americans.
The Afghan defence ministry said violence broke out between an Afghan air force pilot and US troops following an argument inside a facility used by the Afghan air force.
General Mohammad Zahir Azimi, a ministry spokesman, said the assailant was killed in the shooting.
"For the past 20 years, he has been a military pilot. An argument happened between him and the foreigners and we have to investigate that," he said.
A statement from the NATO-led International Security Assistance Force (ISAF) said eight of its troops had been killed, but did not immediately disclose the nationalities of the victims.
" A quick reaction force responded to the incident", the statement said.
The Taliban claimed responsibility for the killings but authorities could not confirm the group's involvement.
A spokesman for the group told Al Jazeera that one of its members had been serving in the army for a long time with the aim of killing foreign forces and finally got the chance.
NATO efforts to train and equip local forces into taking over responsibility for security across Afghanistan by 2014 have been hit by a string of attacks carried out by men who have apparently infiltrated the armed forces or who committed attacks wearing unauthorised uniforms.
The defence ministry in Kabul was targeted last week by a gunman in army uniform wearing a suicide vest, in an attack that left three people dead.
Earlier this month, an attack at a military base in the east killed nine including five foreign troops and four Afghan soldiers, while the police chief of Kandahar in southern Afghanistan was also assassinated.
There are about 130,000 international troops serving in Afghanistan although Afghan forces are in control of
security in Kabul.
Limited foreign troop withdrawals are due to begin in July ahead of a complete pull-out of international combat troops in 2014.