Saudi Arabia says it shot down Scud missile fired from Yemen

Blames Iranian-backed Shiite rebels known as Houthis and their allies

Saudi Arabia said it shot down a Scud missile fired by Yemen's Shiite rebels and their allies early today at a Saudi city that is home to a major air base, marking what could be a major escalation in the months-long war.

Two missiles launched from a Patriot missile battery shot down the Scud around 2:45 am today (local time) around the southwestern city of Khamis Mushait, the official Saudi Press Agency reported. The agency did not report any casualties in the attack.

Khamis Mushait is home to the King Khalid Air Base, the largest such facility in that part of the country. Saudis on social media reported hearing air raid sirens go off around the city during the attack.

The agency blamed Iranian-backed Shiite rebels known as Houthis and their allies in forces loyal to former Yemeni President Ali Abdullah Saleh.

Saudi Arabia leads a coalition targeting the rebels in airstrikes that began March 26 in support of the country's exiled President Abed Rabbo Mansour Hadi. Those strikes have targeted arms caches and other Scud missile sites around the country.

The coalition responded to today's attack by targeting and damaging the launcher, which was located south of the Houthi hub of Saada, according to the news agency.

Saudi Arabia is the world's largest oil exporter. Its major oil fields are located in the east of the country, far from Khamis Mushait.

The Houthis began their advance in September, sweeping into the Yemeni capital, Sanaa, and taking over government ministries and other areas. They held top officials, including Hadi, under house arrest until Hadi fled, first to the southern port city of Aden, then to Saudi Arabia as the rebels closed in backed by forces loyal to Saleh.

The Saudi-led air campaign and ground fighting have killed more than 1,000 civilians and displaced more than 1 million people since mid-March, the spokesman for the UN secretary-general, Stephane Dujarric, told reporters Wednesday.

The offensive has so far failed to force the Houthis to withdraw from any territory they hold or blunt their advance in southern Yemen.

Yesterday, the Houthis and Saleh's forces launched a ground offensive targeting the Saudi border, which saw the kingdom fire artillery and launch Apache attack helicopters, the Saudi Press Agency reported.

The agency reported "scores" of rebel forces being killed in a battle that lasted from dawn to noon yesterday, with four Saudi soldiers killed in the fighting.