The same day that prosecutors in Las Vegas said criminal charges related to the October mass shooting at a concert are still possible, Denver and Colorado lawmakers proposed a ban on bump-stocks.

The firearm modification would use the force of the gun's kickback (usually a long gun) to turn what the law says can only be semi-automatic fire into near automatic fire. It was used to kill dozens of people and injured hundreds in Las Vegas last year.

Charges are most likely to be brought against Marilou Danley, the shooter's girlfriend at the time.

The bump stock ban proposal in Denver cleared its first hurdle after city councilors voted unanimously to pass a bill banning the devices.

It's more of a symbolic move than anything, as Denver already bans the assault weapons that those attachments are meant for. The bill would also limit rounds in a magazine to 15 from 21.

A final vote on the bill is expected next week.

A similar law has been proposed at the state level. At the time of this writing, the bill has only one Democratic sponsor.