Twitter has been a key tool for ISIS. Not only has the terrorist organization used it to promote its executions and movements, but hacker groups have taken over government and news outlet accounts and used them to promote the ISIS message. Now, reports show that ISIS has called for the death of Twitter's founders and employees.

Buzzfeed News discovered on Sunday that ISIS posted a message on justpaste.it calling for the death of Twitter founder Jack Dorsey and his employees. Not only did the writer blatantly call for Dorsey's death, but the message also had an image of Dorsey with a crosshairs on his forehead.

This isn't just a generic claim about ISIS destroying Twitter. The author of the message requests that Muslim "jihadis" take out all Twitter employees: "For the 'individual jihadi' all over the world, target the Twitter company and its interests in any place, people, and buildings, and don't allow any one of the atheists to survive," the message reads.

This post occurred after Twitter deleted a number of ISIS-related accounts that were posting calls for violence against various groups. Such posts are against the rules of Twitter, whose terms of service bar users from posting "direct, specific calls for violence against other groups." For example, one of the banned accounts implored Muslims to attack police and government officials in the United States, U.K. and France. According to the author, "You started this failed war. We told you from the beginning it's not your war, but you didn't get it and kept closing our accounts on Twitter, but we always come back."

While the message does resemble past ISIS communications, it's unclear who the author was or why the person chose to host it on justpaste.it.

Twitter told Buzzfeed News that "our security team is investigating the veracity of these threats with relevant law enforcement officials."