Peopl use a tug boat to flee Yemen's southern port city of Aden on May 5 amid fighting between Houthi fighters and the Popular Resistance Committees. (Reuters)

Yemeni rebels fired rockets and mortar rounds into Saudi Arabia on Tuesday, killing at least three people, and they reportedly captured five soldiers as the insurgents demonstrated their ability to carry out assaults despite weeks of Saudi-led airstrikes against them.

Saudi Arabia’s state airline canceled flights into the border area of Najran, and schools closed early amid the attack, the first by the Houthi rebels to target a civilian area in the kingdom since the start of the airstrikes. Meanwhile, hundreds of families fled the southern Yemeni port city of Aden after the Houthis advanced into their neighborhoods.

In Najran, the shelling killed two Saudi civilians and damaged buildings, Yemeni tribal leaders said. The official Saudi Press Agency carried an Interior Ministry statement saying three people had been killed; it did not specify whether they were all civilians.

The tribal leaders, who spoke on the condition of anonymity for fear of reprisals, also said that the Houthis captured five Saudi soldiers in unclear circumstances.

In a statement, Saudi Brig. Gen. Ahmed Asiri said Saudi-led coalition forces continue to respond to the Houthi attack.

Fighters of the anti-Houthi Popular Resistance Committee secure a highway road linking Yemen's capital Sanaa with southern provinces May 5. (Reuters)

Asiri’s statement did not offer any details about casualties, and it did not mention the alleged abduction of the soldiers. Saudi Apache helicopters attacked Houthis near the border, said another military official.

Last week, three Saudi troops and dozens of rebels were killed in the fighting there.

The Saudi-led coalition began bombing the Houthi rebels and their allies March 26 in support of exiled President Abed Rabbo Mansour Hadi’s embattled government. The airstrikes and fighting on the ground have killed hundreds and displaced at least 300,000 Yemenis.

In Aden, residents said Houthis advanced into a large section of the city’s Tawahi district, forcing hundreds of families to flee in boats. The residents said they had been trapped in their homes for weeks.

Aden, which Hadi had declared a temporary capital before fleeing for Saudi Arabia, is one of the main battlegrounds in a war that the United Nations and aid organizations warn is pushing Yemen into a humanitarian disaster.

Meanwhile, member states of the Gulf Cooperation Council held a summit Tuesday in Riyadh to discuss the situation in Yemen. At the summit, French President François Hollande threw his country’s support behind the Saudi-led offensive in Yemen. During his opening speech, he said France will not hesitate to act, even militarily, to help its allies.