Houthi rebels struck Riyadh’s King Khalid International Airport on Thursday, the third straight day of attacks on the Saudi capital, sending oil prices sharply higher.

The Iran-backed Houthis claimed the attack. The Saudi-led coalition said it intercepted two ballistic missiles headed for Riyadh and another toward Khamis Mushait. Debris from an interception damaged a kindergarten and a medical complex.

Hundreds of flights to and from Riyadh were cancelled, according to flight-tracking site FlightAware. Witnesses reported explosions and smoke near the airport.

The strikes followed an attack on an oil and chemical tanker near Qatar late Wednesday, which officials in the region blamed on Iran. Brent crude, the global benchmark, traded above $105 a barrel.

Analysts say Tehran is trying to regain leverage in the Strait of Hormuz standoff and press Washington toward a diplomatic settlement.

The Saudi-led coalition said it destroyed Houthi military targets in response. The back-and-forth has turned the Red Sea and the Gulf into the most dangerous shipping lanes in the world.

Global markets are watching closely. Oil traders are pricing in the risk that sustained attacks could disrupt physical supply from the world’s most important crude-exporting region.