NIAMEY, Niger (AP) — Gunmen kidnapped an American citizen in the West African nation of Niger early Tuesday and demanded a ransom from his relatives, a local government official said.

Philipe Nathan Walton was taken from his farm in Massalata in southern Niger at 1:45 a.m., Ibrahim Abba Lele, a prefect in Birni-N’Konni town, told The Associated Press.

The kidnappers called and demanded ransom from Walton’s father, who lives approximately 1 kilometer (about half a mile) away from his son’s farm, said the official. The attack has not yet been claimed and police are investigating, he said.

A spokesperson for the U.S. state department said it is aware that an American citizen was abducted in Niger and is providing support to the family and working with local authorities to carry out search efforts.

Niger has faced a growing number of attacks by extremists linked to both the Islamic State group and to al-Qaida. The kidnapping comes two months after Islamic State-linked militants killed six French aid workers and their Niger guide while they were visiting a wildlife park east of the capital.

Tuesday’s kidnapping brings to seven the number of foreign hostages believed to be held by extremist groups in Niger.

Extremists are kidnapping westerners in the Sahel region to “advance their goals, whether for ransom, for the spotlight, or to amp up the pressure on local and international governments,” said Laith Alkhouri, a counterterrorism specialist at CTI-ME, an intelligence advisory group based in Dubai.

“Militant factions will continue to resort to kidnappings as it has proven advantageous for their operations in West Africa,” he said. The Islamic State group is believed to be holding one other American, Jeffrey Woodke, who was abducted from his home in Abalak, Niger in 2016. Woodke had been in Niger for nearly three decades providing humanitarian services and disaster relief, according to a video message released by his wife to the kidnappers two years ago.

A German, Jorg Lang, who was kidnapped in April 2018, is also believed to be held by the IS group.

Four other foreign hostages believed to be held by al-Qaida-linked militants are from Romania, Australia, Colombia and South Africa.

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Associated Press writer Sam Mednick in Ouagadougou, Burkina Faso contributed.