The city of Oakley in eastern Contra Costa County is still responding to a ransomware attack that knocked its computer network offline and prompted a declaration of a state of emergency, city officials said.

The city activated its Emergency Operations Center after a ransomware attack on Thursday afternoon.  

A ransomware attack occurs when someone encrypts files and demands ransom to decrypt them. The encryption makes the files and the systems that rely on them unusable, according to the U.S. Cybersecurity and Infrastructure Security Agency.   

“Since the incident began, the City’s IT Division, with the help of cybersecurity, forensics and technology experts, has been conducting incident response and analysis, as well as working to recover from and remediate the incident,” the city said in a release sent out Sunday.  

The city has not identified details of exactly how systems were affected, but building, business licenses, engineering and planning services continued to be impacted as of Sunday night.  

Administrative, code enforcement and recreational services are expected to return to “substantially normal” on Monday, the city said.  

The city also said phone services have been restored, though emergency services such as 911, police, fire and ambulance were never impacted by the attack. 

Assistant City Manager Danielle Navarro said Friday that they are committed to being as transparent as possible with the community without compromising the investigation.  

An unpleasant intrusion

The City of Pleasant Hill’s computer servers were also a target of cyber intrusion last week.

The incident occurred Thursday afternoon, police said, without providing details.

Information technology professionals detected the intrusion, which “was quickly isolated in order to minimize any damage,” police said in a statement.

“City services remained operational at all times, and public safety was never compromised,” police said.

Bay City News staff Pete Young contributed to this report.

Katy St. Clair got her start in journalism by working in the classifieds department at the East Bay Express during the height of alt weeklies, then sweet talked her way into becoming staff writer, submissions editor, and music editor. She has been a columnist in the East Bay Express, SF Weekly, and the San Francisco Examiner. Starting in 2015, she begrudgingly scaled the inverted pyramid at dailies such as the Vallejo Times-Herald, The Vacaville Reporter, and the Daily Republic. She has her own independent news site and blog that covers the delightfully dysfunctional town of Vallejo, California, where she also collaborates with the investigative team at Open Vallejo. A passionate advocate for people with developmental disabilities, she serves on both the Board of the Arc of Solano and the Arc of California. She lives in Vallejo.