Middle Eastern terror group ISIS has apparently threatened the lives of Twitter's employees, as well as that of its chairman, Jack Dorsey. The threat was reportedly made as a response to the service's policy of blocking accounts that directly encourage acts of violence or illegal activities such as terrorism. BuzzFeed has translated portions of the message, part of which reads "when our lions come and take your breath, you will never come back to life."
As TechCrunch comments, it seems odd that Twitter alone would be threatened, when other sites like Facebook and YouTube have similarly deleted material. Because the document was uploaded to anonymous sharing site JustPaste, it's not entirely clear if the message originally came from the group's leadership. As far as Twitter is concerned, however, it is taking the threats seriously and is now working with local law enforcement.