The U.S. Marshals Service says it was the victim of a significant ransomware attack earlier this month.

U.S. Marshals Service spokesman Drew Wade said in a statement to multiple media outlets that on Feb. 17 the bureau "discovered a ransomware and data exfiltration event affecting a stand-alone USMS system."

While the system was not connected to a larger federal network, it contains “law enforcement sensitive information, including returns from legal process, administrative information, and personally identifiable information pertaining to subjects of USMS investigations, third parties, and certain USMS employees,” Wade said.

The system was disconnected from the network, and the Justice Department is conducting a forensic investigation, according to Wade.

After being briefed on the cyberattack, senior Justice Department officials determined it constituted “a major incident,” the spokesman said.

The Office of Management and Budget defines a major incident as either one that is likely to cause significant harm to national security interests, foreign relations, the U.S. economy, or the public confidence, civil liberties, public health or safety of Americans, or one that involves personally identifiable information that can potentially be used to cause the aforementioned methods of harm. 

NBC News first reported on the incident Monday. Spectrum News has reached out to the U.S. Marshals Service for comment.

The Marshals Service, part of the Justice Department, is the law enforcement arm of the federal courts. The bureau’s duties include arresting fugitives, managing and selling criminals’ illegally obtained assets, housing and transporting federal prisoners, and operating the Witness Security Program.