Army teams and planes searched the desert nation Monday for three Spanish volunteers kidnapped by gunmen, and Spain's interior minister said he suspected al-Qaida-linked Islamists were behind the attack.
The three aid workers were in a 4-wheel drive vehicle at the very back end of a convoy when the attack happened Sunday in the West African country.
"I think the others heard shooting, and when they stopped, the car was empty," said Julia Tabernejo, a spokeswoman for Barcelona-based aid group Barcelona Accion Solidaria. "Those three were no longer in it."
She identified the missing aid workers as Albert Vilalta, Roque Pascual and Alicia Gamez. The two men are businessmen and are about 50 years old, and she said Gamez is a civil servant in the court system.
A Spanish foreign ministry official, who spoke on condition of anonymity in line with ministry rules, said the aid workers were abducted after two of the 13 vehicles became separated from the convoy for unknown reasons.
A ministry statement said Mauritanian forces are now accompanying the rest of the convoy at Spain's request.
A Mauritanian police official said the aid workers were attacked while delivering supplies to villages along a 240-mile (400-kilometer) road that links the capital, Nouakchott, to Nouadhibou to the north. He asked that his name not be used because he was not authorized to speak to the media.
Spanish Interior Minister Alfredo Perez Rubalcaba told reporters on Monday that he feared the kidnapping was the work of extremists.
"All signs are that it is a kidnapping," he said in Brussels as he entered a meeting with European Union officials. "If that is the case, as I fear it is, everything suggests it is a kidnapping by AQMI, which is al-Qaida in Islamic North Africa. It would not be the first kidnapping it has carried out in that area of European or American aid workers."
Mauritania, once known as a predominantly moderate Muslim nation on Africa's western coast, has been rocked by attacks by the North African al-Qaida group.
The Islamist group operates mainly in Algeria but is suspected of crossing the country's porous desert borders to spread violence in the rest of northwestern Africa.
In June, American Christopher Leggett, 39, was fatally shot in the Mauritanian capital, not far from a school that he helped run. The North African al-Qaida group claimed responsibility, saying they killed the Tennessee native because he allegedly was trying to convert Muslims to Christianity.
In 2007, gunmen in Mauritania killed four French tourists that were picnicking on the side of a highway. In 2008, the world famous Dakar Rally auto race was canceled after organizer's received threats of a possible attack.
Elsewhere in West Africa, the group also has claimed responsibility for the kidnapping of two U.N. staffers in December, and the kidnapping of four European tourists a month later. One of the four Europeans, a Briton, was killed by his captors. The U.N. staffers and the other tourists were released.
Associated Press Writer Daniel Woolls in Madrid contributed to this report.