Hackers have shut down key computer systems in the US city of Atlanta, Georgia and are demanding $51,000 in Bitcoin to reenable the affected systems, Fortune reports today, March 23.

Atlanta’s Mayor Keisha Lance Bottoms announced the attack in a press conference on Thursday, March 22. She told members of the press that officials “don’t know the extent [of the attack] or if anyone’s personal data or bank accounts will be compromised. All of us are subject to this attack.”

The attack was first discovered at 5 a.m. on March 22. The City of Atlanta noted that the “outages” were affecting systems some customers use to pay bills and access court-related information.

City officials are reportedly working with the FBI, the US Department of Homeland Security, and Microsoft to ascertain the extent of the breach and how to resolve it. On March 23, city officials encouraged citizens to monitor their personal information and accounts if they believe their personal information could be compromised in the hack.

As of press time, the situation is yet to be resolved. Bitcoin is currently trading at an average of $8,500, which means the demanded ransom would cost the city approximately 6 bitcoins.

This is not the first instance of hackers holding municipal computer systems hostage in exchange for cryptocurrency. In November 2017, a hacker attacked the Sacramento Regional Transit system for a ransom of 1 bitcoin, which at the time of the attack was worth about $8,000.

In a more malicious example of ransom for Bitcoin, a parcel bomber in Germany demanded a €10 mln ransom to be paid in Bitcoin in a message sent to a Potsdam Christmas market in December 2017. The package, which failed to detonate, contained a QR code for depositing bitcoins, in addition to explosive materials derived from fireworks and nails.