Five Cameroonian soldiers were killed by separatist fighters during an attack overnight into Tuesday in the country’s restive English-speaking region of Northwest, according to military sources.

The separatist fighters ambushed and attacked a military outpost in Lassin village of Noni subdivision of the region, two senior security officers who asked not to be named told Xinhua.

In a video released on social media, separatist fighters who called themselves “Marine Force of Ambaland” claimed responsibility for the attack and warned of “more attacks in future.”

Government forces have been clashing with separatist fighters since 2017 in Cameroon’s two English-speaking regions of Northwest and Southwest where separatists seek to create a breakaway state they call “Ambazonia.”