The U.S. and Israel have been conducting strikes against targets in Iran since Saturday morning, with the aim of toppling Tehran’s clerical regime. Iran has fired back, with retaliatory assaults featuring missiles and drones targeting several Gulf countries and American bases in the Middle East.

“All six aircrew ejected safely, have been safely recovered, and are in stable condition. Kuwait has acknowledged this incident, and we are grateful for the efforts of the Kuwaiti defense forces and their support in this ongoing operation,” Central Command said.

“The cause of the incident is under investigation. Additional information will be released as it becomes available,” it added.

In a separate statement later Monday, Central Command said that American forces had been killed during combat since the strikes began.

“As of 7:30 am ET, March 2, four U.S. service members have been killed in action. The fourth service member, who was seriously wounded during Iran’s initial attacks, eventually succumbed to their injuries,” it said.

Major combat operations continue and our response effort is ongoing. The identities of the fallen are being withheld until 24 hours after next of kin notification,” Central Command added.

This story has been updated.