PORTLAND, ORE. -- Dozens of people wearing militarized body armour are arriving early for a right-wing rally Saturday in Portland, Oregon that is expected to attract thousands who support President Donald Trump and his "law and order" reelection campaign as tensions boil over nationwide following the decision not to charge officers in Louisville, Kentucky, for killing Breonna Taylor.

Two hours before the event was to start, dozens of people began showing up, some packed into the beds of pickup trucks. Almost everyone was wearing some sort of militarized body armour, including helmets and protective vests. Many flew American flags or black flags bearing the logo of the Three Percenters, another far-right group and some wore Make America Great Again hats.

The Proud Boys, a group that has been designated as a hate group by the Southern Poverty Law Center, described it as a free speech event to support Trump and the police, restore law and order and condemn anti-fascists, "domestic terrorism" and "violent gangs of rioting felons" in the streets. Local and state elected officials forcefully condemned the event and rushed to shore up law enforcement ranks as left-wing groups organized several rallies to oppose the Proud Boys' message.

Oregon Gov. Kate Brown on Friday said she was sending state troopers to help the Portland police and was creating a unified command structure among city, regional and state law enforcement -- a tactic that essentially circumvents a city ban on the use of tear gas as a crowd-control measure. The state police said a "massive influx" of troopers would be in Portland by Saturday morning.

"This is a critical moment. We have seen what happens when armed vigilantes take matters into their own hands. We've seen it in Charlottesville, we've seen it in Kenosha and, unfortunately, we have seen it in Portland," she said, referencing deaths in Virginia, Wisconsin and Oregon during clashes between those on the right and left of the political spectrum.

"The Proud Boys and Patriot Prayer groups have come time and time again looking for a fight, and the results are always tragic," said Brown, a Democrat. "Let me be perfectly clear, we will not tolerate any type of violence this weekend."

The Proud Boys are self-described "Western chauvinists" and they have held multiple events in Portland since Trump's election alongside other right-wing groups such as Patriot Prayer that often end in violent clashes with left-wing counter-demonstrators.

Last month, Aaron "Jay" Danielson, a Trump supporter and Patriot Prayer follower, was shot and killed after some vehicles in a pro-Trump car caravan diverted into downtown Portland and crossed paths with left-wing activists. The suspect in the shooting, a self-described anti-fascist, was killed the following week by law enforcement as they tried to arrest him in Washington state.

The Proud Boys mentioned Danielson in their permit application, as well as Kyle Rittenhouse, the 17-year-old charged in the shooting deaths of two Black Lives Matter protesters in Kenosha, Wisconsin. Some attending Saturday's rally carried signs that said "Free Kyle Now."

Rittenhouse's attorneys have said he was acting in self-defence. The Proud Boys raised the spectre of a vigilante response to the actions of a "mob" in a permit application filed with the city this week.

"Portland leadership is unwilling to stop the violence," the Proud Boys wrote in the application. "They have been blinded by their hatred of our President and will not allow outside help stopping the violence."

Portland Mayor Ted Wheeler said the city and its police force did not need or want help from "paramilitaries or vigilante groups."

Police have cancelled all scheduled days off for officers Saturday and will primarily be focused on keeping dueling groups of protesters separated.

Deputy Chief Chris Davis acknowledged that Oregon is an open-carry state for firearms. But he reminded those attending the rally and counter-demonstrations that under Portland law, it's illegal to carry a loaded firearm in public without an Oregon concealed handgun permit. Officers will patrol for weapons and check for permits as needed, he said.

"We ask that you come peacefully and engage in your free speech peacefully," Police Chief Chuck Lovell said. "It's OK for us to disagree about things. But at the end of the day, doing so peacefully, letting people exercise their rights safely is very important. So that's my ask the folks who are attending."

The rally comes as Portland approaches its fifth month of almost nightly protests against racial injustice and police brutality.

Demonstrators want the city to take millions from the police budget and reallocate it to support the Black community. Some also are angry with the mayor -- who is also the police commissioner -- for allowing police to use tear gas until recently and for what they call overly aggressive police tactics. Wheeler has also refused to cede control of the police bureau to a Black city councilwoman with a decades-long resume of activism around police reform.

Associated Press reporter Sara Cline in Salem, Oregon, contributed to this report.