The Islamic State, also known as ISIS or ISIL, released a graphic video claiming responsibility for their deaths on Sunday. The clip showed the body of one of the activists, his throat slit, along with a warning to the group’s opponents.

“You will never be safe from the blade of the Islamic State, and our hand will reach you wherever you are to slit your throat,” it said.

One of the men, Ibrahim Abdel Qader, was a co-founder of Raqqa Is Being Slaughtered Silently, a group of citizen journalists and human rights activists that uses social media to document abuses committed by the jihadist group in Raqqa, the Syrian city it uses as its headquarters.