(NewsNation) — The Los Angeles Police Protective League (LAPPL), the union serving members of the Los Angeles Police Department, is suing Police Chief Michael Moore and the city after the department released the names and photos of numerous undercover officers through a public records request.

The lawsuit comes after a technology watchdog group posted the information and photographs of more than 9,300 officers in a searchable online database using details it obtained from a publicly available records request. Some of the information in that request included details about undercover officers that were supposed to be withheld.

The suit accuses the city of perpetrating “one of the worst security breaches in recent memory” after it released photographs of undercover officers without notifying them or their union beforehand.

According to an exhibit in the lawsuit, Moore later acknowledged the mistake and apologized in an email to LAPD personnel, writing, “appropriate safeguards were not put in place to ensure those assigned to sensitive investigations were not included.”

In the same email, Moore said he was launching an investigation to determine what happened and vowed to hold those involved accountable.

The officer data was released after a local reporter, Ben Camacho, filed a lawsuit against the LAPD when the department denied his request for employee headshots. The city attorney’s office determined that the agency was required to turn over the information under California’s public records law.

When the LAPD fulfilled the records request, it inadvertently included information about undercover officers that was meant to be left out, the Los Angeles Times first reported.

“It’s a historic level of incompetence on behalf of the management of the Los Angeles Police Department that caused this leak to occur,” Robert Rico, in-house counsel with the Los Angeles Police Protective League, told NewsNation last week. “And we’ve had hundreds of officers who have notified us that they are not only in fear for their safety but for the safety of their families when you have online websites as a result of this historic, incompetent leak, calling us and expressing fear at a level that we’ve never seen.”

In an email exchange, Camacho’s lawyers were told by the city attorney that the undercover officers’ information would be excluded in the final response, but it didn’t happen that way.

The officers’ details were then posted in a database by the Stop LAPD Spying Coalition, a watchdog group, for the sake of “police accountability” and “transparency.”

The database included personal information like name, ethnicity, rank and date of hire. The watchdog group told NewsNation it did not receive or release any officers’ personal addresses.

The police union previously filed a suit against a man they said “intentionally inflicted emotional distress” by citing the information from the records release, after he used language on his Twitter account that insinuated he was calling for violence against officers.

Twitter suspended the user, Steven William Sutcliffe, according to the Los Angeles Times.