CHICAGO -- Chicago police say they're cracking down on people selling guns and drugs on Facebook.
Police announced the arrests of 53 people as part of their undercover investigation known as "Operation Facebooked."
Officials say the weapons and drugs were being sold in private or invisible Facebook groups.
The CPD's Bureau of Organized Crime said typical Facebook users cannot find these groups with a simple search.
They have to be invited inside.
Chicago's interim police chief called out Facebook on Tuesday, claiming the social media giant is not doing enough to stop criminals.
Facebook has not responded to the police department's criticism.