Mayor Ted Wheeler proposed an emergency ordinance Monday afternoon that will allow Portland police to separate dueling protest groups that have turned the streets of downtown Portland into battlegrounds.

The new rules will allow officers to require protesters with a history of violence to gather in designated areas, where police will have an easier time keeping adversaries separated.

"I will not allow continued, planned street violence between rival factions to take place in Portland, Oregon," Wheeler said at a press conference this afternoon. "I have also asked my staff to evaluate options to hold accountable those who recklessly drain our public safety resources by using our city as a venue for planned street violence."

Wheeler says City Council will likely vote on the ordinance this week.

The change comes on the heels of a melee outside Kelly's Olympian bar on Oct. 13, where the right-wing groups Patriot Prayer and the Proud Boys brawled with antifascists. Police faced renewed scrutiny for failing to keep the two groups apart—and making no arrests during the mayhem.

This weekend's brawl mirrored a riot on June 30 that left one man in the hospital with a brain hemorrhage.

Today, Wheeler said that prior to an Aug. 4 rally, the Portland Police Bureau discovered right-wing protesters who had positioned themselves on the roof of a building with a cache of firearms.

What began in the spring of 2017 as improvised confrontations in downtown parks—usually marked by insults and culminating in a punch or two—has grown into chaotic rolling brawls that rage the length of a city block. Patriot Prayer and the Proud Boys have made Portland their primary destination for antagonizing masked antifascists.

Antifa has often taken the bait, throwing punches and deploying bear spray on helmeted right-wingers who use flag poles as weapons. The fights, which often pit one unlucky person against half a dozen adversaries, are bloody beatings, drawing national scorn.

Portland city officials say they cannot stop right-wing groups like Patriot Prayer from demonstrating, even though their rallies often devolve into violence. They point to First Amendment protections established by federal courts that do not allow prior violence to be the basis of banning a protest.

Instead, police will use the city's new ordinance to keep warring protesters far enough apart that people cannot exchange blows.

Correction: This post has been changed to make clear that City Council still must vote on the ordinance. The date the guns were found has been corrected.