Five soldiers from Niger and three United States Army Special Forces personnel were killed in an ambush on a joint operation in the West African country on Wednesday, Reuters reported citing Nigerien and United States officials. Two US personnel were also injured in the attack.

The two forces were conducting a joint routine patrol near the Niger and Mali border when they were attacked. It was unclear who fired first, a United States official said. “We can confirm reports that a joint United States and Nigerien patrol came under hostile fire in southwest Niger,” a spokesperson for the United States Africa Command said.

An official from Niger said that the attackers had come from Mali.

African security forces have stepped up their efforts to counter jihadist groups being formed among the people near the deserts of Sahel. Terrorist groups including the al Qaeda in Islamic Maghreb and the Islamic State in the Greater Sahara have reportedly been active in the region.