Minnesota Gov. Tim Walz has activated the state’s National Guard following a cyberattack on the state’s capital, Saint Paul. City officials have not yet disclosed the nature of the cyberattack, but the July 25 breach continues to disrupt city operations and some public services. 

Saint Paul is one of the largest cities in the U.S. with more than 300,000 residents, and is the latest in a list of major cities targeted by hackers and ransomware gangs in recent years.

In a statement on Tuesday, Walz said he authorized the National Guard’s cyber forces at the city’s request to help Saint Paul recover from the cyberattack, saying the “magnitude and complexity” of the breach exceeded the city’s capacity to respond to the incident.

The National Guard will help to “ensure continuity of vital services and the safety and security of Saint Paul residents,” Walz said. 

Saint Paul Mayor Melvin Carter said in a press conference on Tuesday that the city took its government systems offline to contain the intruders, which sparked a citywide Wi-Fi outage.

Carter added that the city does not store much data on its residents, but said there was a risk that data on city employees had been stolen.