Computers were offline, offices were closed and city government's website was down on Friday as New Orleans officials sought to contain a cyber attack against its network that started in the early morning.

By late afternoon, the city had found no sign that any passwords were compromised or data lost in the attack, though an influx of suspicious emails meant city systems would be kept offline temporarily out of what Chief Information Officer Kim LaGrue described as an abundance of caution.

Asked at a 4 p.m. press conference whether any systems were compromised, LaGrue said, "There’s not that evidence; we have not confirmed that yet. But we did confirm that there was activity."

It was not clear how long city systems will remain offline as officials look into the attack. Investigators from the city have been joined by experts from the Louisiana State Police and National Guard, the FBI and the Secret Service.

In the meantime, officials said, crucial public safety services are still up and running, and City Hall offices will fall back on pen and paper to continue doing business.

The exact nature and extent of the attack were unclear, but it appears to have started about 5 a.m., when city officials first noticed suspicious activity on their network. Reports of suspicious activity picked up as employees got to work around 8 a.m., and officials decided to shut down the system after 11 a.m.

Announcements over the City Hall public address system instructed employees to turn off and unplug their computers.

"That’s the advice we got from our federal and state partners, and that’s the way our security team has been trained to respond," LaGrue said.

City technology officials then went from floor to floor to confirm all systems were offline, Mayor LaToya Cantrell said.

LaGrue said there was evidence of both phishing attempts, or emails that try to trick users into revealing their usernames and passwords, and ransomware, which blocks access to computers and tries to extort money out of their owners.

No city employees reported providing login information in response to the emails, LaGrue said, crediting that response to cybersecurity training that started in the fall. It was unclear Friday whether any ransomware had been installed or had begun to encrypt any city systems.

Cantrell said no requests for money had been made as a result of the attack.

State government was hit by a ransomware attack last month, though it was able to restore its system without giving in to demands. Gov. John Bel Edwards declared a state of emergency, and the state Office of Motor Vehicles was hit especially hard, with many of its offices forced to close for several days.

Several school systems and local governments in Louisiana have dealt with such attacks this year as well. Major cities such as Baltimore and Atlanta have also been hit in recent years.

Officials said that taking the computer systems offline could result in inconvenience but that city government would continue to operate.

"One positive about being a city that has been touched by disasters ... is our plans and our activities reflect the fact that we can operate without the internet and without a city network," said Collin Arnold, New Orleans' homeland security director.

Emergency services, such as police and Emergency Medical Services, were able to continue responding to calls using their radio equipment. Dispatching from the Orleans Parish Communication District, which runs the city's 911 and 311 lines, was unaffected.

The Criminal and Civil District Courts were also unaffected.

New Orleans city government under cyberattack; workers told to turn off, unplug computers Workers in New Orleans City Hall were told a cyberattack has struck the city government, multiple sources said on Friday.