A security incident at Planned Parenthood’s Los Angeles (PPLA) branch compromised personal data of about 400,000 patients, officials confirmed this week.

News of the breach was confirmed in letters sent to affected patients. These state suspicious activity was detected on the PPLA network on Oct. 17, 2021. Following its discovery, PPLA took its systems offline, notified law enforcement, and hired a third-party security firm to aid in its investigation.

The investigation revealed an unauthorized person gained access to PPLA systems between Oct. 9 and Oct. 17 and exfiltrated files. On Nov. 4, officials learned the type of information compromised. In its letters, PPLA wrote “we identified files that contained your name and one of more of the following: address, insurance information, date of birth, and clinical information, such as diagnosis, procedure, and/or prescription information.”