MGM Resorts International said it’s investigating a cyberattack that forced the gaming company to shut down certain systems, in a Monday post on X, the social media site formerly known as Twitter.

Multiple reports indicate guests were unable to use digital room keys, payment systems were not working and hotel restaurants could only accept cash. MGM issued an update Monday night on X saying its dining, gaming and entertainment venues were fully operational and that guests were still able to access their hotel rooms. The front desk at MGM properties were ready to assist guests as needed.

The company said it has notified law enforcement and brought in outside cybersecurity experts to assist in the investigation. 

“The FBI is aware of the incident, as it is still ongoing, we do not have any additional information to provide at this time,” a spokesperson said via email. 

MGM said the investigation is ongoing, and it is “working diligently to determine the nature and scope of the matter, according to its social media post. 

The Retail & Hospitality ISAC, an information sharing site for cybersecurity professionals, said it shares information proactively and reactively throughout the year, but could not provide any additional information due to confidentiality agreements. 

MGM Resorts includes more than 30 hotel and gaming properties in the U.S. and abroad. A spokesperson for the city of Las Vegas referred questions to county officials.

MGM previously suffered a massive breach, as the personal data of about 10.6 million customers was posted on a hacking forum in 2020.