Three US service members were killed and dozens wounded during an unmanned aerial drone attack on US forces stationed in northeastern Jordan near the Syrian border, Reuters reports.

“While we are still gathering the facts of this attack, we know it was carried out by radical Iran-backed militant groups operating in Syria and Iraq,” Biden said in a statement.

At least 34 personnel were being evaluated for possible traumatic brain injury, a US official told Reuters.

“We will carry on their commitment to fight terrorism. And have no doubt - we will hold all those responsible to account at a time and in a manner of our choosing,” Biden said in his statement released by the White House.