Iran fired six ballistic missiles and 29 drones at Saudi Arabia’s Prince Sultan air base in a Friday attack, according to a person briefed on the assault.

The Iranian assault wounded at least 15 U.S. service members, including five who were seriously hurt in the attack, according to the person who was not authorized to comment publicly and spoke on the condition of anonymity. U.S. officials initially reported that at least 10 U.S. troops were injured, including two who were seriously wounded.