(NIAMEY, Niger) — Unidentified gunmen killed six French aid workers and two Nigerien guides who were visiting a wildlife park east of Niger’s capital early Sunday, authorities from both countries said. French President Emmanuel Macron expressed his condolences and support for the victims’ families in a statement. Macron had a phone call with Niger President Mahamadou Issoufou on Sunday evening and both heads of state stressed that “all means are and will be used to clarify the circumstances of the deadly attack,” the statement said. Macron and Issoufou are determined to “continue the fight against terrorist groups” in Africa’s Sahel region. The attack took place in Koure, where Niger has a giraffe reserve, Oumarou Moussa, the adviser to Niger’s interior minister, told The Associated Press.