Two laptop computers containing the names and Social Security numbers of about 40,000 current and former employees of the Chicago Public Schools were stolen from district headquarters April 6.

While school district officials promised tighter security, Chicago Teachers Union President Marilyn Stewart said she’s “furious” about the breach that left employees vulnerable to identity theft.

“I’m furious, I’m outraged, and I’m disgusted,” Stewart said in a statement. “My members are once again victims of a lapse of security on the part of CPS.”

Stewart said the theft was the third security breach involving employees’ personal information in less than six months. In November, former employees’ identifying information was included in a mailing about health insurance. In January, employee W2 forms were distributed improperly, she said.

The laptops, which belong to an accounting firm and its subcontractor, contain the names and Social Security numbers of current and former CPS employees who contributed to the system’s Teacher Pension Fund from 2003 to 2006.

Schools CEO Arne Duncan on April 9 said the district plans to buy a year of credit and identity-theft protection for affected employees.

The district also offered a $10,000 reward for information leading to an arrest or the recovery of the computers and was working closely with police as of press time,

Duncan said.

School Board President Rufus Williams said the district is making changes to reduce its reliance on Social Security numbers to track employees.