The Anonymous hacker group declared war on ISIS following the recent Paris attacks, and has started leaking the personal information of suspected extremists.

According to a report by The Independent, the group is assembling lists of the Twitter accounts and websites of extremists.

Details of the suspected terrorists also include a physical address of someone its says is an ISIS recruiter in Europe.

“Anonymous from all over the world will hunt you down. You should know that we will find you and we will not let you go. We will launch the biggest operation ever against you,” said the hackers.

“Expect massive cyberattacks. War is declared. Get prepared.”

According to a report by Tech Insider, the online collective has been working in earnest against ISIS since the Charlie Hebdo attacks in January.

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