SANAA, Yemen (AP) — Yemen's Houthi rebels have killed three Saudi border guards in a mortar attack, the Saudi Defense Ministry said Saturday, as a plane loaded with medical aid arrived in the rebel-held Yemeni capital.
An unnamed military official quoted in the Defense Ministry statement said the incident took place Friday in the Saudi border province of Najran.
The Defense Ministry said its forces responded with gunfire, and that 500 Houthi fighters have been killed in clashes along the border since a Saudi-led air campaign against them began late last month. Earlier this month, three Saudi border guards were killed in separate clashes with the Houthis.
A plane loaded with badly needed aid meanwhile landed in Yemen's rebel-held capital, Sanaa, on Saturday.
Photos posted on the official Twitter account of the International Committee of the Red Cross showed aid workers unloading the supplies. The group said the shipment consists of more than 35 tons of medical aid, generators and emergency sanitation equipment.
The first such delivery to the capital since the airstrikes began more than two weeks ago landed on Friday. Saturday's shipment was more than double the size of the previous one.
The Saudi-led coalition has imposed a virtual air and sea blockade on Yemen to prevent the Houthis and their allies -- loyalists of former autocrat Ali Abdullah Saleh -- from rearming. Saudi Arabia's regional rival Iran supports the Houthis, but both Tehran and the rebels deny it has armed them.
Aid groups say they are struggling to cope with the rising casualty numbers and shrinking food and fuel supplies. A smaller aid delivery arrived in the southern port city of Aden by boat earlier this week.
Aden, where Yemen's internationally recognized President Abed Rabbo Mansour Hadi had set up a temporary capital before fleeing the country last month, has seen intense fighting in recent days.
Medical officials in Aden said the Houthis and their allies fired mortar shells into two residential areas on Saturday, killing two civilians and wounding at least 25 others.
Eyewitnesses and security officials said Saleh loyalists have taken over a number of buildings and hotels in Aden and are using them to house troops and store weapons.
In the southern Ibb province, tribal officials and eyewitnesses said a local tribe launched an attack on positions held by Houthis and pro-Saleh gunmen.
All officials spoke on condition of anonymity because they were not authorized to speak to reporters. Eyewitnesses requested anonymity because of security concerns.
Mohammed Ausaj, spokesman for the al-Qafer tribe, said the fighting in Ibb raged into Saturday afternoon and that more anti-Houthi tribal fighters were massing in a nearby district.
Hamed al-Bukheiti, a Houthi official, said the rebels have secured the al-Qafer area following clashes with al-Qaida militants. The Houthis refer to most of their opponents as al-Qaida.
The fighting has created an opening for Yemen's powerful al-Qaida affiliate to seize territory, but it was not immediately clear if the extremist group was involved in the fighting in Ibb.