A demonstration in support of Second Amendment gun rights drew left-wing counter-protesters Saturday in Seattle, forcing dozens of police to keep the two sides separated.

Conservative groups Washington 3 Percenters and Patriot Prayer held their “Liberty or Death” rally outside Seattle City Hall, to oppose a city gun-control initiative, while a group of left-wing organizations rallied nearby.

The left-wingers -- including members of Organized Workers for Labor Solidarity, Radical Women and the Freedom Socialist Party -- yelled and used cow bells and sirens in an attempt to drown out speeches from the other side.

One person on the gun-rights side, sporting a Donald Trump hat, was treated for an injury at the scene. A police spokesman told the Seattle Times that a total of three men were arrested for misdemeanor assault.

As tensions mounted, additional police arrived, including some in riot gear. Bicycle officers lined up their bikes as a type of moving barrier to keep protesters from entering the street.

The gun-control initiative would expand background checks, raise the age for people buying semi-automatic rifles from 18 to 21, and create standards for safely storing firearms.

On Friday a judge threw out 300,000 signatures necessary to put the initiative on the November ballot on the grounds that it did not meet election-law requirements. The Alliance for Gun Responsibility, the group behind the proposal, has appealed the motion.

Saturday’s protest came two weeks after police in riot gear in Portland, Ore., tried to keep right-wing and left-wing groups apart. The effort mostly succeeded, but police were accused of being heavy-handed, prompting the city's new police chief to order a review of officers' use of force.

The Associated Press contributed to this report.