RIYADH, Saudi Arabia: A large column of black smoke was seen near Riyadh's main airport on September 19 after loud booms were heard in the Saudi capital and authorities issued overnight warnings about possible aerial attacks.

Reuters video and photographs showed a huge plume of black smoke rising near the airport. The airport highway, main terminal and other facilities could be seen in the foreground. At one point, flames appeared to rise from behind what looked like fuel storage tanks.

The Saudi government's media office did not immediately respond to Reuters questions about the cause of the smoke or the overnight warnings.

Saudi civil defense sent phone alerts to people in Riyadh and Al-Kharj, a city east of the capital, warning them of a possible danger from aerial attacks. Authorities later issued an all-clear in the morning.

A journalist in Riyadh's Olaya district reported hearing several loud booms before the all-clear was issued.

Saudi Arabia has issued some alerts in Riyadh since the start of the US-Iran war, but the warnings on September 19 were the first in the capital since the latest escalation involving Yemen's Houthi group began in July.

The Houthis control Yemen's most heavily populated areas and much of the north of the country. Since July, the Iran-aligned group has launched attacks against Saudi Arabia after declaring a naval blockade against the kingdom.

The group has targeted Saudi vessels in the Red Sea as part of the escalation. Its attacks have also threatened Saudi cities and energy infrastructure, raising concerns about the security of global oil supplies.

The fighting has also put pressure on the Red Sea shipping route, an important alternative for Gulf oil exports, while shipping through the Strait of Hormuz remains blocked.

The latest tensions followed a statement on September 18 by Houthi military spokesperson Yahya Saree. He said the group had stopped what he described as unspecified criminal attempts in the Yemeni capital, Sanaa. He blamed Saudi Arabia and said the Houthis would respond.

The Houthis have made rapid territorial gains in Yemen this month, including taking control of the country's entire Red Sea coastline. The group says Saudi Arabia's air force has carried out hundreds of airstrikes against Houthi targets in recent days.

The escalation has drawn international concern due to its potential impact on civilians and energy infrastructure.

The UN Security Council has condemned the continuing Houthi attacks against Saudi Arabia, including strikes affecting civilian and energy facilities that have injured civilians, including women and children.

The Security Council also condemned what it described as the Houthi military escalation in Yemen.

"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," the Security Council said in its statement.