(CNN) French forces freed four hostages, including an American and South Korean, during a night-time rescue in Burkina Faso in which two soldiers were killed, according to a statement from France's Elysee Palace on Friday.

The US military supported the French-led operation between Thursday and Friday in the northern Sahel region, according to two US officials.

The Elysee statement added that two of the hostages were French citizens, named as Patrick Picque and Laurent Lassimouillas.

The identity of the kidnappers is still unknown, and the American and South Korean hostages, who are female, remain unnamed.

Picque and Lassimouillas were kidnapped on May 1 while in the neighboring West African country of Benin, according to the Elysee. Their safari guide was found dead in Pendjari National Park and their vehicle was burned, Reuters reported.

French soldiers Cedric de Pierrepont, left, and Alain Bertoncello were killed in the operation.

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