Two female Belgian tourists and their driver have been killed after gunmen ambushed their convoy in eastern Yemen, officials say.
The survivors and bodies of the two victims have been flown to Sanaa
Four other Belgians were hurt in the attack in the province of Hadramut.
The Yemeni authorities have launched a hunt for the attackers, who they believe to be al-Qaeda militants.
Last July, seven Spaniards and two Yemenis were killed when a suicide car bomber attacked a group of tourists visiting a temple in central Yemen.
The Belgian tourists were attacked as they travelled through Wadi Dawan, a desert valley about 300km (180 miles) east of the capital Sanaa.
Survivor Karina Lambert said the convoy was ambushed by four gunmen hiding behind a truck parked at the side of the road.
"They immediately started firing on three of the jeeps, the fourth one was further back so it was not hit," she said in a telephone interview with Belgian TV.
"They wanted to kill, that's sure because after the first bursts of machine-gun fire, they approached the vehicles and fired into the cars."
There are reports of a fourth fatality, with Reuters news agency citing the victim as a Yemeni national.
Belgian Foreign Minister Karel De Gucht identified one of the victims as Claudine Van Caille, 65, from Bruges. The family of the other female victim has not yet been informed.
Mr de Gucht said he was horrified by the attack and that he had sent a "clear message" to the Yemeni government to hunt down the killers.
Tourists are often drawn to Wadi Dawan area to visit the famous multi-storey mud buildings in the nearby town of Shibam.
Al-Qaeda has been blamed for a series of attacks in Yemen, the ancestral home of the group's leader Osama Bin Laden.
Tourists flock to see the historic mud tower blocks of Shibam
In July 2006 seven Spanish tourists and their two local drivers died when a suicide bomber rammed his car packed with explosives into their vehicles.
That was the most deadly attack on Westerners in the country since 17 US soldiers aboard the USS Cole were killed when the ship was attacked by al-Qaeda militants as it rested in port in Aden.
In recent years Yemen's government has been fighting Islamists with the help of US special forces based in Djibouti, on the Horn of Africa.