Boko Haram leader, Abubakar Shekau, has claimed responsibility for the mass killings in Baga, Bornu State, and has threatened more violence.

The acknowledgment from the leader of Nigeria’s Islamic extremists comes in a video posted on YouTube Tuesday, the same day International Criminal Court prosecutor Fatou Bensouda said she is examining the allegations and will prosecute those most responsible for war crimes.

According to a translation from Arabic provided by SITE Intelligence Group, Shekau said: “We are the ones who fought the people of Baga, and we have killed them with such a killing.”

Amnesty International says as many as 2,000 civilians were killed and 3,700 homes and business were destroyed in the 3 January attack. The Nigerian military, however, said only 150 deaths were recorded.  Baga and a key military base remain under Boko Haram’s control.