At least three U.S. service members and one contractor were killed in an explosion triggered by an improvised explosive device near Bagram airbase in Afghanistan.

“Three U.S. service members and one contractor were killed, and three U.S. service members were wounded by an improvised explosive device April 8 near Bagram Air Base,” the NATO-led Resolute Support mission said in a statement.

The statement further added that the wounded service members were evacuated and are receiving medical care.

The identities of the deceased service members and the contract have not been disclosed.

“In accordance with U.S. Department of Defense policy, the name of the service members killed in action are being withheld until 24 hours after notification of next of kin is complete,” the statement added.