A high profile hacking group claims it has breached multiple FBI-related services and stolen data “on all FBI employees and applicants.” A representative of the group, called Shiny Hunters, told 404 Media the data includes FBI agents’ names, home addresses, phone number, and information on their spouse. The data breach could be massively significant and may have all sorts of national security and counterintelligence implications.

The representative provided 404 Media with a sample appearing to contain the personal data of 5,000 FBI employees. That data included an alleged address, phone number, date of birth, and in some cases details on their spouse. 404 Media put some of the sample phone numbers into open source intelligence tool OSINT Industries and found they did correspond to people with the same name as listed in the sample file.

Shiny Hunters also defaced the FBI jobs website on Tuesday. The defacement says, “this site has been seized by Shiny Hunters,” which is an obvious nod to the seizure notices the FBI and other law enforcement agencies often put on sites after taking them down. The representative said Shiny Hunters carried out the hack on Monday night.

After publication of this article, an FBI spokesperson told 404 Media in an email “The FBI is aware of claims regarding unauthorized activity affecting FBIjobs.gov and is currently investigating.”