Unknown assailants engaged a group of Afghan and U.S. forces during a joint operation in Nangarhar province of Afghanistan.

Colonel Sonny Leggett, a spokesman of the U.S. forces in Afghanistan confirmed the incident but did not elaborate further regarding the incident.

“A combined U.S. and Afghan force conducting an operation in Nangarhar Province was engaged by direct fire on Feb. 8,” Col. Leggett said, adding that “We are assessing the situation and will provide further updates as they become available.”

Nangarhar is among the relatively volatile provinces in East of Afghanistan where both Taliban and ISIS affiliates are active in some of its districts.

The Afghan and U.S. forces regularly conduct counter-terrorism operations against the two groups in the restive districts of Nangarhar.

The anti-government armed elements have not commented regarding the incident so far.