Three foreign civilians training Afghan national security forces in the western part of the country were killed Sunday by two individuals wearing Afghan army uniforms, officials said.
"Three contracted civilian employees were killed by two individuals wearing Afghan army uniform in western Afghanistan," an official with the NATO-led forces told dpa.
"One of the individuals was killed in the engagement and one of them escaped from the base. We are looking for him."
The incident took place in Herat in western Afghanistan in a Regional Training Center for the Afghan Police and the Afghan Border Police. The nationality of the deceased was not confirmed by the NATO officials. Local media, quoting Afghan officials, said they were Americans. The killer was reportedly an Afghan soldier guarding the training premises.
Another foreigner and an Afghan translator were also injured in the shootout, according to officials. The killing of the trainers put the number of people associated with the NATO-led alliance killed in the past 24 hours at 13 - eight foreigners and five Afghans.
Attacks by uniformed gunmen on foreign troops have increased this year. Since January, there has already been 21 incidents, including this one, in which 30 people have been killed, according to officials.
Last year, 35 soldiers were killed in 21 incidents.
Also, on Sunday, two soldiers were killed in a roadside bomb in southern Afghanistan, the NATO-led military alliance said in a statement.
Earlier, in another statement, it had said two International Security Assistance Force service members died Sunday following a roadside bomb attack in eastern Afghanistan.
Taliban sources were not immediately available for comment.