— US Customs and Border Protection announced Monday photos of travelers and license plates were recently compromised in a data breach.

In a statement, CBP said it learned on May 31 that a subcontractor "had transferred copies of license plate images and traveler images collected by CBP to the subcontractor's company network. The subcontractor's network was subsequently compromised by a malicious cyber-attack."

The agency has notified Congress and is working with law enforcement and cybersecurity entities to "determine the extent of the breach and the appropriate response," according to the statement.

The Washington Post first reported on the data breach.

CBP said its own systems had not been compromised, and the agency writes that, as of Monday, "none of the image data has been identified on the Dark Web or internet."

The subcontractor "violated mandatory security and privacy protocols outlined in their contract," according to CBP, which said it was unaware of the image copies transfers.

"CBP takes its privacy and cybersecurity responsibilities very seriously," the statement reads, "and demands all contractors to do the same."

This is a breaking story and will be updated.