A plume of black smoke was seen over Riyadh airport on Saturday, as Saudi Arabia confirmed Yemen’s Houthi rebels tried to attack its capital with a ballistic missile.

The smoke rose from what appeared to be fuel tanks near the King Khalid International Airport, while flights were disrupted temporarily. At one point flames were visible, although no casualties or damage were reported.

An alert was sent to residents in the capital urging them to stay indoors, the first such alert since this recent escalation. Saudi civil defence sent the alerts for potential danger of aerial attacks in Riyadh and ​the city of Al-Kharj ⁠east of the capital by phone overnight on Friday , before issuing an all-clear on Saturday morning.

Houthi military spokesperson Brig. Gen. Yahya Saree claimed they attacked with cruise and ballistic missiles as well as drones. The Houthis said the operation came as a response to an attack in the Yemeni ⁠capital Sanaa.

They claimed they had targeted “sensitive sites” in Riyadh and facilities of Saudi oil giant Aramco in Yanbu, causing “massive fires.”

A Saudi statement, released long after the attempt on Saturday morning, confirmed Houthi rebels had attempted to attack the capital. It was the first attack targeting Riyadh since the escalation in fighting between the Iran-backed Houthis and Yemeni government forces backed by the Saudis.

They also said the Houthis tried to attack civilian infrastructure in the Red Sea port city of Yanbu and in Taif, Baysh and Farasan but they were thwarted, giving no further details.

The growing conflict near another important global shipping corridor has brought new pressures for markets.

The Houthis, who control the most populous parts of ‌Yemen and much of the north, have been launching attacks against Saudi Arabia since declaring a naval ‌blockade against Riyadh in July, with strikes targeting Saudi vessels in the Red Sea.

The attacks have targeted Saudi cities, energy infrastructure and shipping, creating new threats to global oil supplies and putting at risk the main alternative Red Sea route for Gulf exports while traffic through the Strait of Hormuz remains blockaded.

Turkish Foreign Minister Hakan Fidan said Saudi Arabia may have military needs due to the ongoing Houthi attacks and ⁠Turkey was ready to help under a trilateral defence pact that also includes Pakistan.

It was unclear what kind of support Turkey might provide but Fidan, in an interview with broadcaster NTV, said Saudi needs could include “some technical issues.”

The agreement signed last month stipulates that an armed attack on any of the three countries would be regarded as an attack on all of them.

On Friday Houthi military spokesperson Yahya Saree said the group had foiled unspecified “criminal attempts” in the Yemeni capital Sanaa, blaming Saudi Arabia and vowing a response.

The Iran-aligned group, which seized Yemen’s entire Red Sea coast in a lightning advance this month, says the Saudi Air Force has conducted hundreds of airstrikes against it in recent days.

The UN Security Council in a statement on Friday “condemned in ‌the strongest terms continued Houthi attacks against the Kingdom ​of Saudi Arabia, including attacks impacting civilian and energy infrastructure, which have resulted in ‌the injury of civilians, including women and children.”

In the statement, the Security ​Council also condemned “Houthi military escalation in Yemen”.