United States is witnessing major protests across many of its cities with curfews being imposed there on Saturday. While clashes over police brutality escalated across America with demonstrators ignoring warnings from President Donald Trump that his government would stop the violent protests “cold.”

Minneapolis, the epicenter of the unrest, was gripped by a fifth consecutive night of violence with police in riot gear firing tear gas and stun grenades at protesters venting fury at the death of a black man during an arrest in the city on Monday.

Among the two dozen cities including Los Angeles, Chicago and Atlanta, administration has ordered people to stay indoors overnight as more states called in National Guard soldiers to help control civil unrest not seen in the United States for years.

Tens of thousands of protesters took to the streets from Seattle to New York, demanding tougher murder charges and more arrests over the death of George Floyd, an unarmed black man, who was pinned to the ground by the knee of a white officer in Minneapolis, Minnesota.

In Los Angeles, officers fired rubber bullets and swung batons during a testy standoff with demonstrators who set fire to a police car.

Police and protesters clashed in numerous cities including Chicago and New York, with officers responding to projectiles with pepper spray while shop windows were smashed in Philadelphia.

President Trump blamed the extreme left for the violence, including widespread looting and arson in Minneapolis, saying rioters were dishonoring the memory of Floyd.

“We cannot and must not allow a small group of criminals and vandals to wreck our cities and lay waste to our communities,” the president said.

“My administration will stop mob violence. And we’ll stop it cold,” he added, accusing the loose-knit militant anti-fascist network Antifa of orchestrating the violence.

Peaceful protests occurred too, including in Toronto as the movement spread beyond America’s borders.

Demonstrators nationwide chanted slogans such as “Black Lives Matter” and “I can’t breathe,” which Floyd, who has become a fresh symbol of police brutality, was heard saying repeatedly before he died.

“We’re not turning the cheek anymore. Black lives matter. They will always matter. And we’re here today to show that,” said makeup artist Melissa Mock, who joined several thousand in a daytime protest in Miami.

Tim Walzs, Governor of Minnesota said that he was mobilizing the state’s entire 13,000-strong National Guard to deal with rioters who have looted shops and set fires in the Minneapolis-St. Paul area.

All major freeways leading into Minneapolis were shut down Saturday night with military helicopters taking to the skies over the area as the state braced for more rioting, arsons and looting with locals saying much of the violence was being perpetrated by outsiders.

Former US President Barack Obama had on Friday expressed the “anguish” of millions of Americans over the death of a black man who was killed by police in Minnesota, saying racism cannot be “normal” in the United States.

“This shouldn’t be ‘normal’ in 2020 America,” Obama said of the death of Minneapolis man George Floyd and several other recent racial incidents in the country.

The police officer who was involved in the incident was arrested and charged with third-degree murder on Friday.

These protests are reminiscent of those that followed the 2017 death of Philando Castile, who was sitting in his car after a traffic stop in a nearby suburb when an officer shot him.

Last year, in June, a young black man was killed by US marshals in Memphis, Tennessee, whose death sparked clashes with police overnight.