Violent activities rise beyond Minneapolis as people continued to protest over the death of an unarmed black man after a white police officer knelt on his neck as he lay on the ground following an arrest.
The arrest of George Floyd was captured by an onlooker's cell phone video that went viral and showed a police officer pressing his knee into Floyd's neck as he moaned: "Please, I can't breathe."
Governor Tim Walz had ordered the National Guard troops to help keep the peace after two previous nights of disturbances sparked by Floyd's death on Monday.
In a late-night Twitter message, President Donald Trump said he would send in National Guard troops to "get the job done right" if the "weak" mayor failed to restore order.
"Any difficulty and we will assume control but, when the looting starts, the shooting starts," Trump wrote.
The mayor had earlier ordered a tactical police retreat from a police station that was set ablaze by the protestors.
Four police officers involved in the arrest of Lloyd, who was accused of trying to pass counterfeit money at a corner store, were dismissed on Tuesday, but unrest has continued unabated.
Sympathy protests erupted on Wednesday in Los Angeles and Thursday in Denver, with freeway traffic, blocked in both cities. In Phoenix, protestors faced off with police in riot gear at City Hall, and a rally was held at the Arizona state Capitol.
Thursday night's disturbances in Minneapolis also spread into the adjacent city of St Paul, the state capital, with fires and vandalism breaking out there.
In contrast with Wednesday night, when rock-throwing demonstrators clashed with police in riot gear, law enforcement in Minneapolis kept mostly out of sight around the epicenter of Thursday's disturbances, the Third Precinct police station.
Protestors massing outside the building briefly retreated under volleys of police tear gas and rubber bullets fired at them from the roof, only to regroup and eventually attack the building, setting fire to the structure as police withdrew.
National Guard troops were absent, as were members of the fire department. Protesters were later observed on the roof, and a crowd of hundreds lingered around the building for hours, feeding flames with hunks of plywood and other debris.
At a news briefing early Friday, Mayor Jacob Frey defended his decision to evacuate the precinct station due to "imminent threats to both officers and the public."
Asked by reporters if he had a response to Trump's tweet, Frey said: "Weakness is refusing to take responsibility for your own actions. Weakness is pointing your own finger at a time of crisis. Donald Trump knows nothing about the strength of Minneapolis. We are as strong as hell."
The Minnesota National Guard said it activated 500 of its soldiers in the greater Minneapolis area, mostly to provide security support to firefighters.
The mayor said many of the troops had been posted around the city to help police prevent looting of banks, grocery stores, pharmacies, and other essential locations during the coronavirus pandemic.
Several other buildings and a car were set ablaze and looters plundered several businesses, including a burning liquor store and nearby discount store that had been ransacked the night before. Fire officials said 16 buildings were torched on Wednesday night.
The upheaval followed concerted efforts by law enforcement officials to ease tensions by promising justice for Floyd.
The Floyd case was reminiscent of the 2014 killing of Eric Garner, an unarmed black man in New York City who died after being put in a banned police chokehold as he, too, was heard to mutter, "I can't breathe."
Floyd was a Houston native who had worked as a nightclub security guard. An employee who called police described the suspect as appearing to be drunk, according to an official transcript of the call.
