The San Francisco city government has formally labelled the pro-gun lobbyist National Rifle Association (NRA) a "domestic terrorist organisation".
The condemnation of the most powerful gun-ownership advocacy group in the US was unanimously passed on Tuesday by the San Francisco Board of Supervisors.
It follows a shooting attack against the Gilroy Garlic Festival, south of the city, which killed three in July.
Democrats have often blamed the NRA's rhetoric for fuelling mass shootings.
The resolution says the US is "plagued by an epidemic of gun violence" and accuses the NRA of using "its considerable wealth and organisation strength to promote gun ownership and incite gun owners to acts of violence".
"All countries have violent and hateful people, but only in America do we give them ready access to assault weapons and large-capacity magazines, thanks, in large part, to the National Rifle Association's influence," the resolution says.
The bill also urges the city and county to reconsider its relationship with companies that do business with the NRA.
The NRA responded by calling it a "ludicrous stunt" that is intended "to distract from the real problems facing San Francisco, such as rampant homelessness, drug abuse and skyrocketing petty crime, to name a few".
District Two Supervisor Catherine Stefani, who wrote the resolution for the Democrat-controlled city, said, "the NRA has it coming to them".
She told KTVU-TV: "The NRA exists to spread dis-information, and knowingly puts guns into the hands of those who would harm and terrorise us."
She told the station that she began writing the resolution after the attack against the Gilroy Garlic Festival in which a gunman killed three people before killing himself.
The resolution was met with fierce criticism from conservative Republicans, who oppose most efforts to restrict private gun ownership, and disagree with many of the policies passed by one of the most liberal cities in the US.
In July, the city Board of Supervisors passed a non-binding resolution calling for the city to cease using terms - such as "felon", "offender", "convict", "addict" and "juvenile delinquent" - and instead use "person first" language.
Instead officials are asked to use language such as "formerly incarcerated person", "justice-involved" person or "returning resident".
That effort was swiftly mocked by conservatives and others, who said the change was unlikely to affect the city's crime rate.