A breach of sensitive information has left the city of Berkeley, Calif., picking up the pieces. In March, the city accidentally included some city employee Social Security numbers when responding to a public records request for salary data by a local a news group.

The city accidentally included the Social Security numbers when the electronic report on employee salaries was sent on March 11 to the Bay Area News Group (BANG), which publishes the salary information annually. According to local media, the city did not realize the sensitive information had been included in the report until the beginning of April.

Nearly a month after the error, the city sent an official letter to all city employees alerting them of the breach.

“We value our employees’ confidentiality and we’re very sorry that it happened,” said City Manager Christine Daniel last Friday in a statement. “All I can say is that it was a mistake.”

According to the city, it had “received confirmation from BANG that it did not disclose any employee Social Security numbers and that it has permanently destroyed the information.”