Notorious internet forum 4chan was hacked on Tuesday. At the time of writing, 4chan’s website was not loading, and users on social media reported the site being intermittently down for hours.

Messages on a rival message board, which TechCrunch has seen, celebrated the hack, with one person claiming that the hacker responsible for the breach was inside 4chan’s system “for over a year.”

Several screenshots showing what appears to be 4chan’s back end circulated online, showing the site’s alleged back end, source code, and templates to ban users, which would only be accessible to the site’s moderators. Also in the leaked data was a list of alleged 4chan moderators and “janitors,” who are users who can delete posts and threads, but have fewer privileges than moderators, who can also see IP addresses of users, for example.