MGM National Harbor affected by ‘cybersecurity issue’ that caused widespread computer outages

A "cybersecurity issue" that led to the shutdown of some casino and hotel computer systems at MGM Resorts International properties across the U.S. is also affecting some operations at MGM National Harbor in Maryland.

The incident began Sunday. MGM Resorts said in a statement it identified a "cybersecurity issue affecting some of the company’s systems" and that its investigation involved external cybersecurity experts.

FOX 5’s Bob Barnard was inside MGM National Harbor Tuesday and said the casino is up and running and dining service is operational. The MGM National Harbor website is currently unavailable. Messages posted online direct guests to call 844-646-6847 for assistance.

The nature of the issue was not described, but the statement said efforts to protect data included "shutting down certain systems." It said the investigation was continuing.

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MGM National Harbor (Barnard / WTTG)

In addition to MGM National Harbor, the incident impacted reservation systems and casino floors in Las Vegas, and in states including Massachusetts, Michigan, Mississippi, New Jersey, New York and Ohio.

The company operates properties across the country and in China and Macau.

MGM Resorts posted an update to X, formerly Twitter, late Monday night.

"As an update to our previous statement, our resorts, including dining, entertainment and gaming are currently operational, and continue to deliver the experiences for which MGM is known," the update said. "Our guests remain able to access their hotel rooms and our Front Desk staff is ready to assist our guests as needed. We appreciate your patience."

The Associated Press contributed to this report