Two U.S. service members were killed in action on Friday in an Iranian ballistic missile and drone attack on U.S. and partner forces in Jordan, U.S. Central Command announced.

A third U.S. service member is missing, the command release added, while four more troops had to be medically evacuated to hospitals in Jordan.

Those four service members have since been discharged, the command added.

“Other personnel who were evaluated for minor injuries have returned to duty,” the release stated.

U.S. Central Command is withholding the identities of the dead until 24 hours after the service members’ next of kin have been notified.

Additional information about the exact location of the attack had not been provided as of publication.

The casualties in Friday’s attack bring the toll of American troops killed in the war with Iran to 16.

Most recently, the commanding officer of the Navy’s Helicopter Sea Combat Squadron 5, Cmdr. Gabriel Edwards, was killed on July 1 when the MH-60S Sea Hawk helicopter he was aboard went down in the Arabian Sea. Three other sailors were rescued following the emergency landing.

More than 400 U.S. troops have been wounded in the campaign, which began Feb. 28.