BALTIMORE — An official with Baltimore mayor's office says the city's IT team is restoring computer systems slowly to ensure their security after a crippling ransomware attack.

The Baltimore Sun reports deputy chief of staff Sheryl Goldstein says the IT team has been split into two groups to help the city's recovery. She says one group is working to find the code that allowed hackers to lock city files, while the other is working to restore affected systems.

The computer servers were hit by the cyberattack May 7 and city officials quickly shut down most servers. Services like online payments and email were affected.

Officials have said hackers using the ransomware variant RobbinHood demanded the city pay the equivalent of $76,000 in bitcoin, which Mayor Bernard Young says won't happen.