Am Law 200 law firm Burr & Forman experienced a data breach that affected nearly 20,000 people, according to a public notice that said the incident occurred when “an unauthorized actor gained access to certain documents and information” on the firm’s systems.

The firm said it was the victim of an October data breach that was “quickly contained.” However, the firm said its analysis indicated the breach impacted the data of two health care clients subject to HIPAA. “We continue to address this matter with those clients directly and to comply with all required notices and actions,” said Kathryn Whitaker, chief marketing officer, in a statement.