The physician group said the compromised data may include names, addresses, Social Security numbers, financial information and limited patient health data. People affected will be notified by mail, the organization said Thursday, Oct. 15.

Sources cited in local reporting identified the ransomware group Chaos as responsible for the intrusion and theft. COPC has not publicly detailed how the attackers gained access. The investigation is continuing.

COPC said the incident has been contained and patients can continue using its MyChart portal. The organization said it knows of no identity theft or fraud connected to the breach so far.

The practice plans to pay for credit and dark-web monitoring for affected people and said a call center would open Thursday afternoon to answer questions. COPC, a physician-founded and physician-led group with more than 80 locations across central Ohio, is one of the largest physician-owned primary care organizations in the country.

In a statement, CEO Don Deep said the organization was implementing additional security measures and that supporting patients’ peace of mind was important. People who receive a notice should review it for details about the information involved and how to enroll in the monitoring services.