The U.S. and NATO Resolute Support mission issued a statement "to clarify initial reporting" about Monday's roadside bombing of an American convoy near the main U.S. base. The Taliban claimed responsibility for the attack.
The mission said a roadside bomb hit the convoy near the Bagram Airfield, killing three American service members, and that "the contractor who was reported as killed, is alive."
The statement said "the contractor, an Afghan citizen, was initially treated along with other injured civilians, later identified as a contractor and treated at Bagram Airfield."
WABC-TV reports that one of the Americans killed was an FDNY firefighter. Christopher Slutman, 43, was a married father of three young daughters. A Staff Sergeant with the U.S. Marine Corps., he was identified by the Kentland Volunteer Fire Department in Landover, Maryland.
Three other U.S. service members were also wounded in the attack. The base in Bagram district is located in northern Parwan province and serves as the main U.S. air facility in the country.
The wounded were evacuated and are receiving medical care, the statement said. It added that in accordance with U.S. Department of Defense policy, the names of service members killed in action were being withheld until after the notification of next of kin.
In their claim of responsibility, the Taliban said they launched the attack and that one of their suicide bombers detonated his explosives-laden vehicle near the NATO base. The conflicting accounts could not be immediately reconciled.
On Tuesday, local Afghan officials said at least five Afghan civilians were wounded in the commotion after the attack on the American convoy.
Four were passers-by and the fifth was a driver of a car going down the road, said Abdul Raqib Kohistani, the Bagram district police chief. Abdul Shakor Qudosi, the district administrative chief in Bagram, said American soldiers opened fire immediately after their convoy was bombed.
Monday's U.S. fatalities bring to seven the number of U.S. soldiers killed so far this year in Afghanistan, underscoring the difficulties in bringing peace to the war-wrecked country even as Washington has stepped up efforts to find a way to end the 17-year war, America's longest.
There are about 14,000 U.S. forces in Afghanistan, supporting embattled Afghan forces as they struggle on two fronts - facing a resurgent Taliban who now hold sway over almost half the country and also the Islamic State affiliate, which has sought to expand its footprint in Afghanistan even as its self-proclaimed "caliphate" has crumbled in Syria and Iraq.
Last year, 13 U.S. service members were killed in Afghanistan.
The Taliban have continued to carry out daily attacks on Afghan security forces despite holding several rounds of peace talks with the United States in recent months. The Taliban have refused to meet with the Afghan government, which they view as a U.S. puppet.
Meanwhile, the Taliban have agreed to take part in an all-Afghan gathering later this month in Qatar, where the insurgents maintain a political office. But the Taliban say they will not recognize any government official attending the gathering as a representative of the Kabul government, only as an individual Afghan participant.
The ABC Owned Stations contributed to this report.