1. MGM Resorts faced a cybersecurity issue characterized as "ongoing" by the FBI.

2. Casino operator MGM Resorts temporarily shut down various computer systems, including its website.

3. The outage affected reservation and booking systems, electronic key card systems, and casino floors.

4. MGM's email systems were also taken down due to the cybersecurity issue.

5. Casino floors were back online, but reservation and booking systems remained down.

6. MGM operates thousands of hotel rooms, with Las Vegas room revenue surpassing casino revenue.

7. MGM initiated an investigation with cybersecurity experts' assistance and notified law enforcement.

8. The FBI acknowledged the incident but provided no further information.

9. MGM's website advised patrons to contact hotels or casinos directly via phone.

10. This incident is not the first cybersecurity issue for MGM Resorts; over 10 million visitor details were leaked in 2020.