SIOUX CITY, Iowa (AP) — Officials say a cyberattacker might have taken patient data from a Sioux City vision and surgical practice. The Sioux City Journal reports that officials for Jones Eye Clinic and an affiliated surgery center, CJ Elmwood Partners, discovered a ransomware attack on Aug. 23. In such online attacks, data is locked and payment demanded for the data to be released. The computer systems were put back into service using backup information, and no ransom payment was made.

Officials say the attackers would have had the ability to access patient information contained in billing and schedule software but not medical records. The compromised patient data included some individuals’ Social Security numbers and insurance claim information. Jones Eye Clinic and the surgery center have told patients about the data breach and are paying to enroll the affected patients in a year of credit monitoring.