An American, described in some media reports as an aid worker, was kidnapped late Friday by an unknown group of assailants in Niger, the U.S. Embassy in Niger confirmed Saturday.

The embassy, in a statement, advised U.S. citizens in the country that the threat of kidnapping and hostage taking "continues to be very high" and cautioned them to take "appropriate security precautions."

The embassy did not identify the hostage or elaborate on the incident except to say that it took place in Niger's Tahoua region, near Mali.

Gov. Daouda Maiga, governor of Mali’s Menaka region bordering Niger, said earlier that several armed men burst into the aid worker’s house and took him after killing two people at the scene, the Associated Press reports.

CNN quotes a government source as saying the aid worker was abducted outside his home by armed assailants who killed his bodyguard and a police officer before fleeing toward neighboring Mali.

The source tells CNN that witnesses say the worker was forced to strip down to his underwear before being putting into a 4x4 vehicle. Such measures are often taken by kidnappers to avoid hostages being tracked.

It was not immediately clear who may have been behind the abduction. While the al-Qaeda terrorist organization has long abducted foreigners and criminals also stage kidnappings for random in the vast Sahel region, Friday night’s abduction is believed to be the first time an American has been taken.

The news organization Les Voix Du Monde (The Voice of the World) said the kidnapping victim works with an organization called Youth With A Mission. The Wisconsin-based Christian missionary organization, founded in 1960, has a staff of 18,000 people in 180 countries.