NEWARK-- Hackers have disabled some City of Newark computers and are now demanding about $30,000 worth of the online currency Bitcoin to render them operable once again, TAPInto reported Monday.

The computers were infected over the weekend with an encryption that affects nearly all files that operate on a desktop, according to a document obtained by TAPInto. Seth Wainer, the city's chief information officer, confirmed that some computers were attacked with a virus since Friday.

Wainer also said the hack has caused a disruption to some city services but police operations were unaffected.

State and federal law enforcement are investigating.

Paul Milo may be reached at pmilo@njadvancemedia.com. Follow him on Twitter@PaulMilo2. Find NJ.com on Facebook.