BEIRUT (AP) — Three Saudi citizens were killed, including a pilot with the national airline, and several other people “of different nationalities” were wounded in attacks targeting Riyadh's King Khalid International Airport and a Saudia Airlines aircraft, the kingdom's civil aviation authority said Friday.

Thursday's attack marked the deadliest in Saudi Arabia since the kingdom and allied forces in neighboring Yemen launched a major military offensive last weekend against Yemen's Iran-backed Houthi rebels.

It was also a significant escalation in the latest front in the Iran war, which has kept oil prices and markets jumpy.

Yemen's Houthis have claimed the attack

The first attack on Thursday afternoon targeted airport facilities, while the second struck the aircraft, the Saudi statement said. It did not identify those responsible, though the Houthis claimed to have targeted the airport with a ballistic missile.

Among the dead was Capt. Hamoud Ali Alkalthami, the Saudia Group said in a statement. It appeared to be the first confirmed attack on the Saudi national carrier since the new offensive began. A separate Saudia Group statement said one of its aircraft was damaged while it was on the ground, with no passengers on board.

The aviation statement also said the injuries to citizens and people of other nationalities “ranged from minor to serious.” The Saudia Group statement said operational activities at the airport returned to normal as of 6 p.m. Thursday, hours after the attack.

Meanwhile, the Saudi-led coalition fighting the Houthis said it had destroyed three rocket launch platforms used by the rebels to threaten regional security.

The Riyadh airport has been repeatedly targeted

The airport in the Saudi capital has come under multiple attacks in recent days. The Houthis this week warned global airlines “for the last time” about the potential consequences of operating in Saudi airspace, which they called a theater for its military operations.

On Wednesday, Saudi officials said attacks on the Riyadh and Abha airports claimed by the Houthis had killed three people.

Saudi Arabia is under increasing attack from the Houthis, who earlier this year declared a blockade of the Saudis in response to one imposed on them.

The kingdom has reached out to allies for support, including the United States. Officials have said U.S. assistance has included intelligence sharing, target identification and planning for the latest offensive.

The new offensive against the Houthis is aimed at retaking territory that the rebels seized a month ago along Yemen’s western Red Sea coast and on the strategic Bab el-Mandeb Strait. The rebels’ presence on the Bab el-Mandeb poses a threat to the crucial shipping alternative to the Strait of Hormuz, where traffic has been curtailed due to Iran’s attacks on ships.

Now, however, regional aviation is also a growing concern. Hundreds of flights to and from Riyadh were cancelled Thursday, according to flight-tracking site FlightAware.

The Indian Embassy later said Air India had suspended operations through Saturday, while the Lufthansa Group said its airlines would suspend flights to Riyadh through Oct. 16. And a U.S. Embassy security alert on Wednesday said citizens should be aware of potential airspace closures.

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Anna reported from Jerusalem.