(NewsNation Now) — U.S. Fertility, which operates more than 55 fertility clinics across the country, announced Thursday that patient data including addresses, social security numbers and possibly protected health information were stolen in a ransomware attack.

U.S. Fertility is one of the largest networks of fertility clinics in the country.

In a statement, USF said that the initial malware infection was detected in Sept. 14, 2020 and that the system was fully reconnected by Sept. 20. After an investigation it was determined the hackers were able to access data between Aug. 12 to Sept. 14.

USF said that it has no evidence of misuse of information as a result of the incident.

This story is developing. Refresh for updates.