Universal Health Services, a major hospital chain operating in the U.S. and Britain, says its computer networks have been knocked offline by an unspecified "security issue."
The Fortune 500 company, which has 400 hospitals and clinics and 90,000 employees, said in a short statement posted to its website Monday that it is working "diligently with our IT security partners to restore IT operations as quickly as possible."
UHS said its "patient care continues to be delivered safely and effectively" and no patient or employee data appears to have been accessed, copied or otherwise compromised. The company's website says UHS treats 3.5 million patients annually.
The company based in King of Prussia, Pennsylvania, did not immediately respond to emails seeking more information.
The cybersecurity news site BleepingComputer said computer and phone systems were knocked offline at UHS facilities starting early Sunday. It quoted reports on Reddit from people identifying themselves as company employees.