Bump stocks were banned by Denver City Council last month in a vote of 11 - 1 after the November massacre in Las Vegas where more than 50 were killed and 500 injured.
The shooter fired from a hotel room at Route 91 Harvest festival goers utilizing a legal method of making semi-automatic weapons near automatic: bump stocks. The stock uses the kickback of the weapon to allow users to pull the trigger almost as quickly as a fully automatic weapon.
The shooter was able to fire 9 shots per second, according to an analysis done by the New York Times.
As a response, Denver banned all ownership of bump stocks. The move was symbolic, as the city bans the types of assault weapons those stocks fit. The bill also limits magazine rounds from 21 to 15.
Denver Police posted on Twitter Friday afternoon warning people to turn in any they may own - or they could face jail time and a fine.
"If Denver residents are in possession of a bump stock, and would like to turn-in their bump stock to the Denver Police Department, they can do so at any Denver Police Station," law enforcement wrote in a news release. "Anyone in Denver who is charged with possessing, selling, carrying or storing a bump stock will be subjected to a fine and/or incarceration."
You could be facing anywhere from 10 to 180 days in jail and anywhere from a $100 to a $999 fine, DPD says.