France's anti-terror prosecutor's office said Monday it would probe the killing of eight people, including French aid workers, by gunmen in Niger. It would investigate charges of murder "with links to a terrorist enterprise" as well as "criminal terrorist association", the office said in a statement. Gunmen on motorcycles killed eight people, including French aid workers, visiting a part of Niger Sunday that is popular with tourists for its wildlife. Local authorities said the dead were six French citizens and two Nigerians -- the group's driver and a tour guide. According to the NGOs ACTED and Impact Initiatives, the victims were seven humanitarian workers and their guide. Paris has confirmed that French citizens were among the dead, without giving a number, and announced France's Barkhane force fighting jihadists in the Sahel region would provide support to Niger's army. No-one has claimed responsibility for the killings, but the region is a known hideout for Sahel jihadist groups such as Islamic State in the Greater Sahara (ISGS). Foreign Minister Jean-Yves Le Drian said Monday that France was "determined to ensure that the protection of humanitarian and health personnel is respected." No means will be spared "to elucidate the circumstances of this murderous attack," he added in a statement. "Our two countries remain determined to continue the joint fight against terrorist groups in the Sahel." bl/mlr/sjw/pma