The Seminole Nation Gaming Enterprise suffered a security breach on Sunday, causing all three of the nation’s casinos to shut down.

As of press time Tuesday, the Seminole Nation Casino at I-40 and Highway 377, the River Mist Casino in Konawa and the Trading Post Casino in Wewoka remained closed due to the breach.

Seminole Nation Chief Gregory P. Chilcoat on Tuesday issued the following statement regarding the May 9 security breach.

“Due to an unforeseen security breach on the Seminole Nation Gaming Enterprise computer systems, the Nation’s casinos are unable to operate fully at this time. The privacy of our guests and employees is our highest priority and we want to make sure this issue is resolved quickly. The appropriate authorities have been notified and we are working with experts to determine any risks to data security,” Chilocat said.

Sunday’s incident was the second major security breach reported in Oklahoma in recent days. Due to a ransomware attack that occurred last week, the City of Tulsa was still experiencing technical difficulties as late as Saturday. The city reported that while no customer information was compromised, residents will see delays in network services.

On a national scale, Colonial Pipeline, which delivers about 45% of the fuel consumed on the east coast, was the victim of a cyberattack last week, causing the demand for gasoline to soar across the country. The attack was attributed to the Russian ransomware group Darkside. Company officials said on Monday they hoped to have its system fully restored by the end of the week.