Oakland was the victim of a ransomware attack that began Wednesday night, police and city officials said Friday.
The city's information technology department is working with law enforcement to determine the scope and severity of the attack.
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.
City officials did not release the amount of ransom the attackers are asking for.
The attack is not affecting residents ability to call 911. Nor has it affected the city's financial data or fire resources. The public also can still file crime reports on the city's website.
Residents and visitors can expect delays in hearing from city staff and officials. Because of the attack, the information technology department has taken down impacted computer systems.
City officials are developing a plan to respond to the attack.
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