Two French soldiers have been killed in a military operation in the West African nation of Burkina Faso that freed two French tourists and two others kidnapped in neighboring Benin.

In a statement Friday, French President Emmanuel Macron expressed condolences for the two soldiers killed in the overnight operation. He promised support to Burkina Faso and Benin in fighting terrorism in the Sahel region. The statement did not indicate who was holding the tourists or the identity of the other two people who were released.

The tourists failed to return from a visit last week to the Pendjari National Park wildlife reserve. Their guide was later found dead.

Islamic extremists have become increasingly active in Burkina Faso, raising worries the militants could be infiltrating northern Benin and neighboring Togo as well.