Mayor LaToya Cantrell has declared a state of emergency in New Orleans, which has ordered the shutdown of most of the city’s computer network following a ransomware attack.

The attack started at 5 a.m. CST on Friday, according to the City of New Orleans’ emergency preparedness campaign, NOLA Ready, managed by the Office of Homeland Security and Emergency Preparedness. The organization tweeted a warning that “suspicious activity was detected on the City’s network.”

At that point, the City’s IT department required the city’s servers to be powered down, with all employees to turn off computers and disconnect from Wi-Fi.

No ransom request has yet been made, and the Mayor indicated emergency services were still operating, with fire and police responding as needed.

State and federal agencies are assisting the city in its recovery and investigation of the attack. There was no word on when full network services would be restored.