Young said on Twitter that essential services like police, fire and 311 are still working, and that city employees are trying to figure out the attack's origin and extent.

"At this time, we have seen no evidence that any personal data has left the system," Young said. "Out of an abundance of precaution, the city has shut down the majority of its servers. We will provide updates as information becomes available."

WBAL-TV 11 reports several people at the Abel Wolman Municipal Building said they couldn't pay fees or fines due to the outage. In response to the issues, the Department of Public Works said late water bill fees would be suspended for Baltimore City and Baltimore County customers.

City officials are calling this a ransomware attack. Essentially, Baltimore's data is being held hostage. The FBI told 11 News it's assisting the city in trying to determine the cause and scope of the virus.

But that information didn't ease frustration for people with tax bills, parking fines and speed camera tickets that are due.

"They told me the system is down. You can't pay nothing. But I have until tomorrow to pay this thing. I've called here about four to five times and nobody will answer the phone," Eddie Tucker said.

There's no proof that any personal data has been compromised, and emergency services are still operational.

"(It's) real frustrating because I need to put my truck on the road because that's how I make my money," Baxter Degraffinried said.

Mayor Jack Young released a statement on Facebook, saying: "Baltimore City core essential services (police, fire, EMS and 311) are still operational, but it has been determined that the city's network has been infected with a ransomware virus. City employees are working diligently to determine the source and extent of the infection. At this time, we have seen no evidence that any personal data has left the system. Out of an abundance of precaution, the city has shut down the majority of its servers. We will provide updates as information becomes available."

Baltimore City Council President Brandon Scott released a statement, saying: "The city of Baltimore's network has been infected with a ransomware virus. Our police, fire, EMS and 311 are still operational. City employees are working hard to identify the source and scope of the virus. As of now, we have no proof that any personal data has left the system. As a measure of caution, the majority of city servers have been shut down. Updates will be provided as information is available."

The Baltimore City Department of Public Works said the issue "has also taken down phone lines to customer support and services, so, for now, we're unable to take calls to discuss water billing issues."

The department has also suspended late water bill fees, saying: "Due to current network issues throughout the city, the director of Public Works has suspended late water bill fees for city and county customers."

The Baltimore City Department of Transportation said the issue is affecting the impound lots at Main Pulaski Facility and the Fallsway Facility and the Right-of-Way Services Division.

The Baltimore City Recreation and Parks Department issued a statement on Twitter, saying: "We apologize for the delay in all communications and are working to solve the problem. Please know our online payment, permit, program registration and service requests are currently effected."

Making money is the whole point of ransomware, according to cybersecurity expert Bill Sieglien.

"The fact that an entire municipality is shut down, all of Baltimore City, should be worrisome to a lot of people," Sieglien said.