The Washington, D.C., Metropolitan Police Department on Monday experienced a large data breach after a ransomware syndicate leaked many of the agency’s police reports, internal memos, and arrest information.

The law enforcement body’s servers were compromised by “unauthorized access,” and the FBI has been called in to lead the investigation, a spokesperson for the department told the Washington Examiner in an email. A dark-web group called Babuk claimed responsibility for the attack, and the group said it had grabbed roughly 250 gigabytes of data.