PORTLAND, Ore. — The mayors of six U.S. cities are appealing to Congress to make it illegal for the U.S. government to deploy militarized agents to cities that don’t want them.

The mayors of Portland, Oregon; Seattle; Chicago; Kansas City; Albuquerque, New Mexico; and Washington wrote to leaders of the U.S. House and Senate pushing for limits on agent deployments.

The move came Monday as a top official said federal militarized officers would remain in Portland until attacks on the U.S. courthouse cease.

Early Monday, U.S. agents repeatedly fired what appeared to be tear gas, flash bangs and pepper balls at protesters.

Federal agents have been patrolling Portland over a little over a week. They were sent to the city by the Department of Homeland Security as part of President Donald Trump's crackdown on the defacement of federal property, statues and monuments.

Protests have taken place nightly in Portland for 60 straight days, since the death of George Floyd at the hands of police in Minneapolis. While the vast majority of those demonstrating have been peaceful, a federal courthouse has been defaced with graffiti, some protesters have thrown fireworks and other projectiles toward officers and others have attempted to breach fencing surrounding the courthouse.

Federal agents have responded by using tear gas, pepper balls and the use of batons to disperse protesters on several occasions. They've also grabbed protesters off the streets and detained them in unmarked cars.

Protests have escalated in intensity since federal agents have arrived in the city, which has forced Oregon Gov. Kate Brown and Portland Mayor Ted Wheeler to call for their removal.

The Portland (Oregon) Police Department said that 49 people were arrested stemming from what the police called “riots” in Oregon's largest city over the weekend.

Sunday marked the 74^th day of unrest in Portland following the Memorial Day death of George Floyd who died while in Minneapolis Police custody. The period of unrest included federal agents engaging with protesters at the city’s federal courthouse, which prompted nationwide scrutiny over the use of federal officers for domestic law enforcement purposes.

Among the demonstrators arrested over the weekend was Demetria Hester, a prominent Black Lives Matter activist who leads the group Mothers United for Black Lives Matter. The 46-year-old demonstrator was arrested Sunday on charges of disorderly conduct and interfering with a peace officer.

Hester testified in a hate crime case earlier this year against a man involved in a sentenced train attack, saying that she had been attacked by self-described white nationalist Jeremy Christian before the deadly incident. Christian wound up be sentenced to life in prison after being found guilty of killing two people in a hate crime.

Friday night marked the most arrests from the weekend, 24, and the injury of an Oregon State Police Trooper, who police said was wounded from being struck in the head by a rock.

The department said that there were two separate gatherings in the city on Friday. The first, the police say, was a peaceful demonstration that officers did not interact with. But a second gathering nearby, the department said, began to turn violent.

On Saturday, a second protest took place and lasted peacefully for four hours, according to police. But tensions began to rise after the group marched, and vehicles began to illegally block intersections.

Some in the crowd then set fire to Portland’s police union building, prompting the department’s officers to engage with the crowd.

“People within the crowd committed crimes when they erected a fence, pushed dumpsters into the street to block traffic, set a dumpster on fire, vandalized the PPA office with spray paint, and destroyed security cameras,” the Portland Police said. “At 11:35 p.m., people within the crowd broke the window to the PPA Office, unlawfully entered, and started a fire, committing the crimes of criminal mischief, burglary, and attempted arson.”

On Sunday, an additional 16 arrests were conducted as two Portland officers were injured by a mortar.