( CNN ) Atlanta 's mayor on Thursday urged anyone with personal information in city information systems to check their financial records as an investigation continues into a r ansomware attack Attack.Ransom on the city . Ransomware is a malicious software that prevents or limits users from accessing their system by locking them out until a ransom is paid. Attack.Ransom NBC affiliate WXIA reported that the city received a ransom demand Attack.Ransom in bitcoin for $ 6,800 per unit or $ 51,000 to unlock the entire system . CNN has not independently confirmed the report . Mayor Keisha Lance Bottoms advised city employees to contact credit agencies and monitor their bank accounts in case their personal data w as compromised. Attack.Databreach She urged the public to take the same precautions while investigators work to determine the scope of the attack . `` We do n't know the extent so we just ask that you be vigilant , '' Bottoms said in a Thursday news conference . `` All of us are subject to this attack , if you will . Many of us pay our bills online , we have direct deposit , so go online and check your bank statements . '' Atlanta Chief Operating Officer Richard Cox confirmed that the city received a written d emand Attack.Ransom related to t he attack. Attack.Ransom When asked in the news conference if the city was going to p ay a ransom, Attack.Ransom Bottoms said , `` We ca n't speak to that right now . '' `` We will be looking for guidance from , specifically , our federal partners on how to best navigate the best course of action , '' she said . The Federal Bureau of Investigation and Department of Homeland Security are investigating the cyberattack , which Atlanta Information Management officials learned of Thursday at 5:40 a.m. , Cox said . DHS spokesman Scott McConnell said the agency offered technical expertise and support and referred questions to the city . The city announced outages earlier Thursday to various customer-facing applications , including those used to pay bills and access court-related information . Thursday afternoon , Cox said several departments were affected , too . Some city data remains encrypted while investigators continue to determine the scope of t he attack, Attack.Ransom he said . The city 's payroll has not been affected , he said . Public safety and water services are operating without incident . The city engaged Microsoft and a team from Cisco 's Incident Response Services in the investigation , Deputy Chief Information Officer Daphne Rackley said . When asked if the city was aware of vulnerabilities and failed to take action , Rackley said the city had implemented measures in the past that might have lessened the scope of the breach . She cited a `` cloud strategy '' to migrate critical systems to secure infrastructure . `` This is not a new issue to the state of Georgia , it 's not a new issue to our country . We have been taking active measures to mitigate any risk in the past . '' In the meantime , the mayor urged caution . `` We do n't know if it 's limited to information related to just our employees or if it 's more extensive than that . But because we do n't know I think that it would be appropriate for the public just to be vigilant in checking their accounts and making sure your credit agencies also have been notified . ''