Explosions rang out in the Saudi capital on Sunday, as the kingdom was due to reopen Riyadh international airport despite repeated attacks by Yemen's Houthis.
Saudi Arabia, which leads a military coalition fighting the Iran-backed Houthis, has faced a barrage of strikes from the group in recent weeks.
The fighting erupted after a years-long truce between the Houthis and Yemen's Riyadh-backed government fell apart.
Riyadh's international airport said flights would resume on Sunday after a two-week closure following the Houthi strikes.
However it remained unclear to what extent the airport was operational.
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The Houthi fighters have carried out waves of strikes on the airport, including an attack this month that killed 13 people and wounded more than 300, the deadliest in the kingdom in more than a decade.
The group has also targeted oil infrastructure and other sites, with the Saudi-led coalition in Yemen announcing on Sunday it had intercepted 10 Houthi missiles fired at southern Saudi Arabia.
Houthi military spokesman Yahya Saree warned that Riyadh airport was still "unsafe" and a "military target".
"The Yemeni Armed Forces warn all international, regional and local airlines — as well as staff and travelers — against using King Khalid Airport in Riyadh, as it is unsafe and serves as a military target for our forces," he said.
"The Saudi regime shall bear the consequences of any operations at the airport."
An AFP journalist in the city heard three explosions in the early hours of Sunday, with residents receiving alert messages for a "hostile aerial threat" urging them to stay in a safe place.
The warning came as the Saudi-led coalition fighting the Houthis said it had downed a ballistic missile launched by the group towards Riyadh, as well as two drones in the capital area.
"Air defences intercepted and destroyed a ballistic missile launched by the terrorist Houthi militia toward Riyadh," the coalition posted on X.
Later Sunday morning, the coalition said its forces intercepted a cruise missile fired by the Houthis at the kingdom's southern city of Khamis Mushait.
Attacks appeared to target areas across the south, with warnings also issued for Abha city and Namas Governorate.
"The bombardment has been very heavy since this morning -- may God keep us safe. Everything is shaking because of the explosions," one resident in Khamis Mushait told AFP Sunday on condition of anonymity.
The attacks came after the Houthi fighters said that — in the space of 24 hours — they targeted three Saudi airports, including in Riyadh, energy installations, a pipeline and an air base.
The Saudi civil defence agency said it had also responded to falling debris in the Mecca and Medina regions on Saturday after intercepting two Houthi missiles.
The Houthis denied targeting the cities, the two holiest in Islam, calling the Saudi claim a "huge lie".
The Houthis also fired at the southern Yemeni city of Aden, the interim seat of the Saudi-backed government, saying they targeted a naval base and military camp overseen by Saudi forces.
The flare-up in Yemen, with the Houthis taking control of the entire Red Sea coast in a lightning offensive last month, has further destabilised the region and disrupted oil markets.
The Houthi attacks have dealt a blow to Saudi Arabia, the world's biggest exporter of crude, disrupting businesses, airlines and residents, and rattling its drive to shift its international image.
