Major US cities -- convulsed by protests, clashes with police and looting since the death in Minneapolis police custody of George Floyd a week ago -- braced Monday for another night of unrest.
Demonstrators took to the streets of more than 140 towns and cities overnight Sunday, US media reported, with many protests turning into running battles with police.
Curfew were renewed in a number of cities on Monday as the country geared up for another night of turmoil.
The Midwestern city where a police officer killed George Floyd by kneeling on his neck for more than eight minutes was calmer overnight after beefing up its security forces.
Thousands of people marched on Sunday to the capitol building in Saint Paul, Minneapolis' twin city and the seat of the state's legislature.
The demonstrators were marching peacefully along a highway when the driver of a speeding tanker truck tried to force his way through the crowd, without causing any injuries. The driver is being investigated by police.
When the curfew began at 8:00 pm for a third night, police fired flash-bang rounds at protesters to disperse them. More than 150 were arrested for breaking the curfew, officials said.
Hundreds of protesters gathered outside the White House on Sunday for a peaceful demonstration that turned more tense once night fell and the crowds grew. Police fired tear gas to drive the crowds away from the presidential seat. In the ensuing melee, American flags were burned, cars were set ablaze, graffiti sprayed on walls and numerous shop windows smashed.
A curfew was introduced for the first time at 11:00 pm, a deadline that was brought forward to 7:00 pm Monday as the city braced for more protests.
According to The New York Times, President Donald Trump was moved by his Secret Service guards to an underground bunker as the protests roiled the park outside.
Between 5,000 and 6,000 demonstrators took to the streets of New York Sunday, police chief Dermot Shea said.
"When it got dark, it got ugly, and it got ugly quick," he said Monday.
New York Governor Andrew Cuomo announced Monday the city would be under curfew from 11:00 pm until 5:00 am Tuesday.
Some police officers took a knee as a sign of support for the demonstrations, the Times said, but violence broke out at Union Square and in Soho, where stores were looted and vandalized.
Among the hundreds of people arrested on four consecutive nights of unrest in the city was the daughter of Mayor Bill de Blasio, Chiara de Blasio, who was briefly detained for unlawful assembly, the Times said.
The city announced a 6:00 pm curfew on Sunday night for the whole of Los Angeles country as National Guard troops with rifles and combat gear began patrolling the city.
On Melrose Avenue, residents used brooms and buckets of water to clean up the debris from the night before. At midday, several hundred people joined demonstrations and later in the night, looting broke out in Santa Monica in the suburbs, including in an upmarket mall.
Police said they had made hundreds of arrests.