Kettering Health said it is experiencing a system-wide outage due to an early morning cyber attack.
A statement from the agency said the shut-down has led to the cancellation of all elective inpatient and outpatient procedures that were scheduled for May 20.
Kettering Health operates 14 medical centers around southwest Ohio, with more than 15,000 employees and 1,800 physicians.
Its call center has also been affected, so anyone calling in may have difficulty getting through.
The hospital network said its emergency rooms and clinics are still operating while they work to restore system operations.
Kettering Health said the incident is the result of unauthorized access to its network. The hospital system said it has taken steps to contain and mitigate this activity and is investigating.
Kettering Health also confirmed reports that scam calls have occurred from people claiming to be with the system, requesting credit card payments for medical expenses. It stated that it has not been established that these scams calls are connected to the system-wide technology outage.
"While it is customary for Kettering Health to contact patients by phone to discuss payment options for medical bills, out of an abundance of caution, we will not be making calls to ask for or receive payment over the phone until further notice," the system stated.
