Two US service members were killed and six others wounded after an attack on a joint US-Afghan operation in the Nangarhar province in eastern Afghanistan on Saturday, US military said in a statement.
The two soldiers killed in the attack were US Special Forces, a defense official said.
Wounded service members were receiving medical treatment at a US facility.
Current reports indicate a person in an Afghan uniform opened fire on the combined US and Afghan forces with a machine gun at the Sherzad district center, said Col. Sonny Leggett, spokesman for the US forces in Afghanistan.
“We are still collecting information and the cause or motive behind the attack is unknown at this time. The incident is under investigation,” Leggett said, according to the statement.
The US military has not determined whether the attack was an Afghan soldier or someone wearing a military uniform, a US official told CNN.
The Afghan Ministry of Defense said in a statement released Sunday that an Afghan soldier was also killed in the attack on the joint US-Afghan operation. The US military has not confirmed the Afghan death.
“As a result, unfortunately, one brave ANA member was martyred and three brave members injured; and two brave Resolute support members lost their lives and six brave members were injured,” the Afghan Ministry of Defense said in a statement.
The ministry added that attacks such as these “fail to have negative effects on the friendship and spirit of cooperation and between the ANDSF and US Military forces. We will continue to fight terrorism together.”
In accordance with US Department of Defense policy, the names of the US service members killed are being withheld until 24 hours after notifying next of kin.
Between 12,000 and 13,000 US troops are currently serving in Afghanistan fighting terrorist groups and assisting local forces in the country.
The Trump administration is weighing further significant troop reductions in Afghanistan, despite a record high number of attacks carried out in the country last year by the Taliban and other anti-government groups.