Yemen's Houthis say they have launched another attack on Riyadh airport and an air base in Saudi Arabia's Khamis Mushait as fighting between the two sides continues.
Saudi Arabia earlier issued an alert for a potential "hostile threat" in Riyadh, according to a message seen by Reuters.
A Saudi-led coalition later said it had destroyed the ballistic missile fired by the Iran-aligned group.
An alert was later issued over a potential danger in Khamis Mushait which officials have since said has passed.
The latest strikes came after Saudi officials launched an investigation into how its air defences failed to intercept the barrage of missiles and drones that struck King Khalid International Airport, killing 14 people and injuring about 320 on the weekend.
The Houthis have been attacking Saudi airports and oil facilities since last week as part of a rapidly escalating conflict that has spilled over from the war between the United States and Iran.
Authorities have extended the closure of the airport until October 17 and airlines have scrapped flights.
UAE airline Etihad said it would not resume flights until next week at the earliest.
Thick black smoke and flames rise from a fire at King Khalid International Airport in Riyadh. (AP)
The Saudi civil aviation authority said work was underway to "allow for the completion of procedures to ensure the safety and operational readiness of the airport's facilities".
Air traffic tracker Flightradar24 showed planes avoiding the city on Monday, though jets were crossing Saudi airspace and landing at the country's biggest airport in Jeddah on the country's west coast.
Officials, who spoke to the Associated Press on condition of anonymity, said an initial probe showed the Houthis first fired multiple drones to pave the way for a mix of cruise and ballistic missiles to reach King Khalid International Airport.
One of the officials said the investigation also aimed to find out why air defence systems did not provide earlier warning of the attack in which the missiles and drones flew more than 1,000 kilometres to reach Riyadh.
"The events of recent weeks are serious," Saudi Energy Minister Prince Abdul Aziz bin Salman told the World Petroleum Energy Congress in Riyadh.
"Our response must be equally serious."
The Saudi government-run Center for International Communication, which oversees foreign media, did not immediately respond to a request for comment.
Strikes have continued between Saudi Arabia and the Houthis, with the rebel group saying one person had been killed and 12 injured in a new Saudi attack on the Yemeni capital Sanaa.
Saudi officials want US more involved
Donald Trump spoke with reporters on Saturday. (AP: Alex Brandon)
The Saudis are looking to the US to become more directly involved in their fight against the Houthis.
The US has provided intelligence sharing, target identification and planning for a Saudi-led offensive — but so far has held off on directly carrying out strikes against the Houthis.
US President Donald Trump on Saturday told reporters that he was looking at the possibility of carrying out US attacks against the Houthis.
Speaking at a conference in Abu Dhabi focused on the postwar future of the Middle East, former US secretary of state Mike Pompeo said the Houthi strike was a troubling development that showed the US had not yet achieved its objectives for the war against Iran.
"What it does demonstrate is that we've not yet achieved deterrence. We collectively have not yet achieved deterrence," said Mr Pompeo, who served as secretary of state and CIA director during Mr Trump's first term.
"You have to crush the Iranian regime, period, full stop. There's no solution short of that."
A US intervention could prompt the Houthis to try to halt shipping through the Bab el-Mandeb Strait at the southern end of the Red Sea off Yemen, restricting the flow of oil out of the Persian Gulf.
UAE diplomat suggests Gulf allies respond to Houthis jointly
Separately, an Emirati diplomat on Monday called for "joint Gulf action" to defend Gulf countries against attacks by Iran and its allies.
Anwar Gargash — a diplomatic adviser to the rulers of the United Arab Emirates — said Iran and its allies wrongly assessed that Gulf Arabs were "the weakest link" in the US war against Iran, during which Tehran and its allies repeatedly attacked Arab countries on the other side of the Gulf.
Anwar Gargash is the Emirati minister of state for foreign affairs. (AP: Ebrahim Noroozi)
"It has become clear that we are all targeted, and that our security is indivisible," he wrote on social media, adding that attacks on Saudi Arabia "undermine the security of the UAE and all Gulf states".
AP/Reuters