Hotel group Marriott International has confirmed another data breach, with hackers claiming to have stolen 20 gigabytes of sensitive data, including guests’ credit card information.

The incident, first reported by Databreaches.net, is said to have happened in June when an unnamed hacking group claimed they used social engineering to trick an employee at a Marriott hotel in Maryland into giving them access to their computer.

“Marriott International is aware of a threat actor who used social engineering to trick one associate at a single Marriott hotel into providing access to the associate’s computer,” Marriott spokesperson Melissa Froehlich Flood told TechCrunch in a statement. “The threat actor did not gain access to Marriott’s core network.”

Marriott said the hotel chain identified, and was investigating, the incident before the threat actor contacted the company in an extortion attempt, which Marriott said it did not pay.

The group claiming responsibility for the attack say the stolen data includes guests’ credit card information and confidential information about both guests and employees. Samples of the data provided to Databreaches.net purport to show reservation logs for airline crew members from January 2022 and names and other details of guests, as well as credit card information used to make bookings.