More than 80 percent of poker machines have been shut down in the state of Arizona.
The Arizona Gaming Control Board said Monday it had suspended the use of nearly 7,000 machines and suspended online gaming at all other casinos.
Arizona Governor Doug Ducey has declared a state of emergency.
The state also has ordered an audit of casino operations to identify what went wrong and to determine what additional actions need to be taken.
The Associated Press contributed to this report.