An unnamed military official quoted in the Defense Ministry statement said the incident took place yesterday 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.
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 yesterday. Today'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.
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 today, 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.
