More than 500 employees of the Fairfax County Police Department — including the police chief — have been notified their personal information may have been compromised by a potential data breach at a neighboring police department, officials said.

Fairfax County Police Chief Col. Edwin C. Roessler Jr. said Friday the department is concerned after learning full names, dates of birth and Social Security numbers for its police officers and other employees were among the data that was on a memory stick that contained the email inbox of the Purcellville police chief. It has disappeared.

Roessler said he has not received any reports from his officers that their data has been exploited, but he worries about their financial and physical safety. Given the nature of the work, officers go to great lengths to protect their personal information.

“This is just devastating,” Roessler said. “I hope it doesn’t create any harm.”

A data analysis firm working for Purcellville informed about 1,800 people late last week of a potential breach that occurred after a copy of Police Chief Cynthia McAlister’s emails disappeared. It was created during an internal investigation in October 2017.

The firm said the inbox contained medical information, bank account numbers and other data for law enforcement officials, crime victims and people who filed police reports from across the D.C. area.

The former publisher of the Loudoun Tribune later claimed to town officials he had access to the emails, although Purcellville officials say they are still trying to determine the veracity of that claim. Brian Reynolds, of Leesburg, was later convicted of fraud and weapons charges and previously had a criminal record. He is currently in prison and his lawyer has not commented on the issue.

Roessler said the department is exploring how data on so many of its employees ended up in the inbox of the Purcellville police chief. Roessler said it is unclear if there was a reason for it to be there or if there was a data breach in Fairfax County as well.

Roessler said he learned via a letter sent to his home that his own data was in the email.