International forces attacked Taliban militants in the Helmand province as they were travelling by motorcycle toward the Pakistan border.
The U.S.-led coalition could not confirm the attack, however, while NATO said they were looking into the report.
Earlier on Thursday a suicide bomber attacked a U.S. military convoy outside Kabul's airport, killing six civilians and injuring over 20 people, Kabul police said.
Four American soldiers suffered minor injuries in the car bomb attack, which also damaged several nearby vehicles and buildings. The Taliban has claimed responsibility for the blast.
On Tuesday, coalition and Afghan forces killed almost a dozen suspected militants in Helmand during a clash in the Garmsir district. The troops had been searching compounds for Taliban weapon traffickers and foreign fighters when they came under fire.
