Government (U.S.) // Maryland, United States
The security breach was detected when a "few dozen" city employees attempted to file tax returns and were rejected, according to officials.
Every employee, retiree and past employee could be affected, officials said.
It is not clear when the data theft happened.
"We have not seen it limited to a specific agency of city government," said Howard Libit, spokesman for Mayor Stephanie Rawlings-Blake.
In the meantime, city officials have shut down online access to payroll and tax information.
An email went out on April 14 alerting all employees to the incident.
Officials suspect that information such as Social Security numbers, names and dates of birth were stolen.