Officials from Columbus Mayor Andrew Ginther's office said Monday that protected health information for fewer than 1,000 people was compromised during the July 2024 cyberattack on the city.
The office said that the information was contained in a Division of Fire database.
The data may have included first and last names, addresses, birth dates, the dates of service runs and brief notes by EMS personnel.
Officials also said a small amount of Social Security numbers were in the data.
Ginther's office said there is no evidence that treatment records or financial information was compromised.
The city is mailing residents whose information was compromised. Affected residents will have 90 days to enroll for two free years of credit monitoring and $1 million of protection against fraud and identity theft.
In September, the city's IT director Sam Orth acknowledged that Columbus residents' data was likely leaked to the dark web.