The city of Atlanta’s computer network was hacked recently by cyberattackers demanding an unnamed ransom amount. The FBI and the Department of Homeland Security have launched an investigation while Mayor Keisha Lance Bottoms warned city employees to monitor their bank accounts for unusual activity.

“We don’t know the extent, so I would ask for people to assume that you may be included,” Bottoms said in a news conference. “Our information management team is working with the FBI, homeland security, also external partners from Microsoft and Cisco Cybersecurity incident response team to help resolve this issue. We have been working diligently all day long to try to come to some type of resolution.”

“This attack has encrypted some of the city data, however, we’re still validating the extent of the compromise,” said Richard Cox, the city’s chief operating officer.

According to Engadget, ransomware locks and holds computers ransom for a specified amount of money, usually cryptocurrency. The site reports attackers are asking for $50,000 in bitcoin from the city.