BAMAKO, Mali (AP) — Gunmen stormed the house of a longtime American aid worker in Niger, killing two people before fleeing with the man toward the border with Mali, authorities said Saturday.

It is believed to be the first time an American citizen has been abducted in the vast Sahel region, where al-Qaida and criminal gangs have targeted French nationals and other Europeans for more than a decade, demanding millions of dollars for their release.

"We are aware of reports of the kidnapping of a U.S. citizen in Niger," a State Department official said after the abduction late Friday. "The U.S. Department of State has no higher priority than the safety and security of U.S. citizens overseas."

There was no immediate claim of responsibility, though al-Qaida-linked militants have abducted foreigners in Niger and brought them to northern Mali before.

The government of Niger said in a news release Saturday that the American had lived there since 1992.

"These criminals are currently en route toward Mali and our forces are pursuing them," the interior ministry said in its statement. "The president of the republic is personally following the situation and our forces are fully mobilized to capture them and put an end to this disastrous affair."

Gov. Daouda Maiga, governor of Mali's Menaka region bordering Niger, said authorities there were alerted to be on the lookout for a white Toyota Hilux, a vehicle often used by jihadists in the region.

The abduction took place in Abalak, in the Tahoua region of Niger. About a week ago, 22 people were killed in a refugee camp some 155 miles (250 kilometers) away.

A number of foreigners remain hostage in the Sahel region, including a Swiss woman and a South African-British dual national, both seized in separate attacks in Timbuktu, Mali. In Burkina Faso, an Australian doctor and a Romanian man are being held captive.

Associated Press writers Matthew Lee in Washington and Krista Larson in Dakar, Senegal, contributed to this report.