Saudi Arabia has launched an investigation to determine how its air defenses failed to intercept a barrage of missiles and drones fired by Iran-backed Houthi rebels, including an attack on Riyadh airport that killed at least 13 people and wounded over 300, two regional officials said Monday.

The officials, who spoke on condition of anonymity because they were not authorized to comment publicly, said the initial probe showed that Yemen's Houthis first fired multiple drones to pave the way for a mix of cruise and ballistic missiles to reach Riyadh's King Khalid International Airport.