As midnight approached in Minnesota, a protest in the Minneapolis suburb of Brooklyn Center over the fatal shooting of 20-year-old Daunte Wright was ebbing into a strained standoff between the police and a few lingering demonstrators.
Colonel Matt Langer of the Minnesota State Patrol told reporters early Tuesday morning that about 40 people had been arrested in Brooklyn Center on a variety of charges including violating curfew and rioting.
Hundreds of protesters assembled outside a police station in Brooklyn Center on Monday evening to demand justice over Mr. Wright’s killing. In a steady rain, they chanted “Killer cop” as officers in riot gear stood guard behind newly erected fencing.
The police declared the gathering unlawful, saying that it violated a 7 p.m. curfew imposed after the shooting on Sunday, and tried to disperse the crowd using tear gas and flash-bang grenades.
Over the next few hours, state troopers and National Guard troops were able to push the crowd several blocks away from the police station. Some businesses near the police station, including a Dollar Tree and a Boost Mobile store, were looted.
Col. Langer said that Minnesota law enforcement officers had hoped to avoid using chemical munitions against protesters, but that the calculus changed after the officers were “shelled, pretty significant, with objects by the crowd.”
“Decisions needed to be made to push that crowd back from the fence,” Col. Langer said. A few officers suffered minor injuries, he said, adding that he was not aware of any injuries to protesters.
By late Monday evening, lines of officers were guarding a perimeter they had established. Only a few dozen protesters remained, and some continued to yell at the police.
Brooklyn Center was not the only place where police officers braced for a night of civil unrest and potential violence following the fatal police shooting of Mr. Wright, who had been pulled over for a traffic violation.
In Portland, Ore., demonstrators gathered at two separate events Monday night, decrying police violence and lighting candles in honor of Mr. Wright. After sunset, a crowd of about 250 people marched to a police precinct, where some lit a fire in an overturned dumpster or threw fireworks toward officers.
The crowd in Portland chanted Mr. Wright’s name, as well as “No cops, no prisons, total abolition.”
“Every city. Every town,” they chanted at another point. “Burn the precincts to the ground.”
In Los Angeles, Sheriff Alex Villanueva girded for violence, saying at a news conference on Monday afternoon that people who “dress like tackle football, with a helmet, goggles and shields, you’re not there to protest peacefully.”
On Monday evening, Mayor Mike Elliott of Brooklyn Center told a group of protesters, “I want you all to stay a good distance from these officers while you’re expressing your voice,” according to a video of the encounter that was posted on Twitter.
“If you know me, I want you to understand that I am going to do absolutely everything in my power to make sure that justice is done,” Mr. Elliott said. “This isn’t going to get swept under the rug or anything like that.”