Denver City Council voted on Monday to ban bump stocks, a device that alters a semiautomatic weapon to have it fire like an automatic weapon.
A bump stock was used to kill dozens of people and injured hundreds in Las Vegas last year.
It's more of a symbolic move than anything, as Denver already bans the assault weapons that those attachments are meant for. The bill also limits rounds in a magazine to 15 from 21.
The ban passed 11 to 1 on Monday night at a Denver City Council meeting.
A similar law has been proposed at the state level. At the time of this writing, the bill has only one Democratic sponsor.