Groton ― Groton Public Schools said personal data ― potentially individual names and Social Security numbers ― may have been accessed in a data security breach this winter, according to a notice sent by an attorney.

The notice stated that after an investigation, the school district determined that “personal data may have been subject to unauthorized access or acquisition” between Jan. 21 and Feb. 1.

“Sensitive data for students and parents, such as Social Security numbers of financial information, were not involved in this incident,” the notice states.

The school district on Friday began notifying people whose information may have been included in the impacted files “out of an abundance of caution,” the notice states. The school district has “no evidence that any personal information has been released or has been or will be misused for identity theft or medical financial fraud as a direct result of this incident.”

The people who were notified have been told best practices to protect their information and have been offered credit monitoring service, the notice states.

The notice states that the school district has been investigating and working with cybersecurity professionals, including the FBI and U.S. Department of Homeland Security, after it experienced a network security incident on Feb. 1.

The school district reported on Feb. 1 that it was “a victim of a cyber-attack on our main servers,” that caused a district-wide internet outage.

“GPS is committed to maintaining the privacy of personal information in its possession and has taken many precautions to safeguard it,” the notice states. “GPS continually evaluates and modifies its practices to enhance the security and privacy of the personal information it maintains.”

The notice states that the school district established a call center to answer questions from people affected by the incident. The call center is available weekdays from 9 a.m. to 9 p.m. Eastern Time at 1-866-680-2738.