OMAHA, Neb. (AP) — Nebraska Medicine and the University of Nebraska Medical Center have begun notifying patients and employees whose personal information may have been compromised in a data security breach last fall.

The breach may have affected up to 219,000 people in Nebraska and other states, the Omaha World-Herald reported Wednesday. Health system officials said in a statement that an investigation begun in late September found no evidence that peoples’ personal information had been used to commit fraud or identity theft.

System technology employees discovered the problem on Sept. 20, finding that an unauthorized party gained access to Nebraska Medicine and UNMC’s shared network using malware between Aug. 27 and Sept. 20. The incident led to the postponement of patient appointments for a time and required staff in the system’s hospitals and clinics to chart by hand.

The incident involved one or more items of information such as names, addresses, health insurance and clinical information being compromised. A limited number of patients’ Social Security numbers also were compromised. The incident did not result in unauthorized access to the health system’s shared electronic medical record application, health system officials said.