Reuters video and photographs showed a huge pillar of black smoke rising in the area, with the airport highway, main terminal building and other facilities in the foreground.
There was no immediate comment from the Saudi government's media office in response to Reuters questions about the smoke and the overnight alerts.
Saudi civil defence sent the alerts by phone for potential danger in Riyadh and the city of Al-Kharj east of the capital, before issuing an all-clear on Saturday. A Reuters journalist in Riyadh's Olaya area heard booms before the all-clear was sent.
Although some alerts had been issued in Riyadh this year after the start of the US-Iran war, these were the first since the escalation began with the Houthis in July.
The Houthis, who control the most populous parts of Yemen and much of the north, have been launching attacks towards Saudi Arabia since declaring a naval blockade against Riyadh in July, with strikes targeting Saudi vessels in the Red Sea.
The attacks have created new threats to global oil supplies, putting at risk the main alternative Red Sea route for Gulf exports while traffic through the Strait of Hormuz remains blockaded.
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 air strikes against it in recent days.
The UN Security Council in a statement "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".
