MGM Resorts didn’t respond to a request for comment, and has only posted vague references to a “cybersecurity issue” on Twitter/X, reassuring guests it was working to resolve the issue and that its resorts were staying open. Guests found themselves waiting in hours-long lines to check in and get physical room keys or getting handwritten receipts for casino winnings as the company went into manual mode to stay as operational as possible. Even websites for its many properties went offline for a while.

MGM, which owns more than two dozen hotel and casino locations around the world as well as an online sports betting arm, reported on September 11 that a “cybersecurity issue” was affecting some of its systems, which it shut down to “protect our systems and data.” For the next several days, reports said everything from hotel room digital keys to slot machines weren’t working. And it may have all started with a phone call, if reports citing the hackers themselves are to be believed. Did prominent casino chain MGM Resorts gamble with its customers’ data? That’s a question a lot of those customers are probably asking themselves after a cyberattack took down many of MGM’s systems for several days.