The incident, which took place in Nangarhar province, occurred after a combined US and Afghan force was returning from a “key-leader engagement,” Colonel Sonny Leggett, a spokesman for US forces in Afghanistan, said in a statement.
“We are still collecting information and the cause or motive behind the attack is unknown at this time,” Leggett added, Reuters reported.
No group or individual has yet claimed responsibility for the attack.
The province has been playing host to activity by the Daesh Takfiri terrorist group over the past several years.
The group emerged in Iraq and Syria in 2014, but was defeated by the countries and their allies around three years later.
It began showing up in Afghanistan towards the end of its maximal presence in those countries, and has been trying to expand its turf in the Central Asian country since the 2017 defeat.
Over the past years, various reports and regional officials have warned about underway attempts by the US to relocate Daesh’s defeated elements to Afghanistan.
Washington and scores of its allies launched an operation in Iraq and Syria after the group started its campaign of bloodshed and destruction there under the pretext of uprooting it. The US-led coalition has sustained a presence in the countries despite the end of Daesh’s reign of terror.