FREDERICK, Md. – Frederick County Public Schools is working to contact 1,000 former students whose data was stolen and posted online for sale, possibly from a breach in the state data system.

District officials announced last week that the names, social security numbers, dates of birth, and other personal information of about 1,000 students was stolen and posted for sale online on a foreign website. The information involves students who attended county schools between November 2005 and November 2006, and was stolen some time before 2010, WTOP reports.

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“It does not appear that the breach occurred from FCPS’s system,” FCPS spokesman Michael Doerrer told the news site. “However, we are required by law to share data with the state department of education, and the format of the data matches the Maryland State Department of education format, and the investigation has also found their systems were attacked.”

The announcement came more than three months after 2010 Catoctin High School graduate Zach Amato, 25, alerted district officials about two websites with the information, one of which has since been shut down. The information remains for sale on the other.

According to The Frederick News-Post:

He provided The Frederick News-Post with a link where the students’ personal information had been posted. A person wrote on the website that he or she was selling a “20k USA ssn database” — meaning the person was selling 20,000 Social Security numbers, as well as the associated birthdays and first and last names.

The seller posted a “free list” of 1,000 names of people and their personal information. The News-Post has confirmed some of the names on the list as former Frederick County Public Schools students.

Amato also identified district graduates and other students across the U.S. by searching names on Facebook.

Amato, who now lives in Pennsylvania, contacted the Pennsylvania State Police and FBI, but they weren’t interested. He also contacted the school district’s IT department in early September, and a worker told him the district is launching an investigation, the news site reports.

After a three month investigation, district officials are now notifying the public and working to contact the former students on the list to offer free identity protection services. The state, meanwhile, is beefing up cyber security.

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“We are not really about pointing fingers about were the breach originated from. What we care most about is helping anyone who may have been impacted by the breach including credit monitoring, identity monitoring and the steps that those thousand people that by the data breach,” Doerrer told WHAG.

The FCPS student data investigation involved the FBI, Maryland State Attorney General’s Office, Maryland State Technology Department, Maryland State Department of Education, and a Multistate Information Sharing and Analysis Center, according to a FCPS news release.