A kindergarten and a medical complex in Riyadh were damaged by debris from a missile interception Thursday, while Yemen’s Houthis have vowed to launch further missions aimed at airports in the Saudi kingdom, the Civil Defence agency said.

The incident occurred after Saudi Arabia’s security concerns have also risen following several times the Houthis have threatened critical infrastructure and aviation operations in the country, which is home to the world’s wealthiest oil reserves. The group said from its military spokesman, Yahya Saree, on Thursday that it had made three attacks at Riyadh airport.

Two witnesses at Riyadh airport said that the fuselage of one of the Saudia’s airplanes was riddled with holes and cracks. Three planes were damaged, the source said, adding that one aircraft had sustained serious damage. The extent of the damage and its effects on operations at the airport were not immediately apparent.

They also alleged the Houthis fired rockets towards an airport in Najran and an airbase in Khamis Mushait. Saudi authorities faced the fallout from unrestricted attacks and interception operations as they made these claims.

Saudi Arabia is spearheading a coalition to back the internationally recognised Yemeni government against the Houthis. The group has ratcheted up threats to Saudi targets on the back of the wider regional conflict with attacks targeting for example airports and oil infrastructure.

Concerns have also been raised regarding the safety of the employees at energy facilities with regard to the latest developments. The Houthis issued a warning on Thursday for anyone working at the Saudi energy facilities to leave after breakouts of oil infrastructure factories, including a major refinery south of Riyadh, were experienced previously.

Saudi Arabia’s energy industrial facilities are vital assets to the energy markets as the world’s biggest exporter of crude oil. Superimposed on the volatility of oil production, refining, and/or transportation could be ripple effects on energy supplies.

This is seen to have heightened security concerns in the entire kingdom since attacks have ramped-up against Riyadh particularly. Authorities still have the difficulty of protecting civilian infrastructure, airports, and energy facilities, as the skirmishing in the region escalates.