The latest episode of violence came after police and federal agents fired tear gas and forcefully dispersed protesters in Portland yesterday
Seattle: Police in Seattle used flashbang grenades and pepper spray Saturday against protesters who set fire to construction trailers outside a youth jail, amid a wave of public anger over President Donald Trump's planned "surge" of federal agents into major cities.
The sounds of repeated small detonations rang out in the streets of the city in Washington state, and smoke rose from an area where demonstrators had set fire to trailers by a construction site for the youth detention facility, an AFP reporter observed.
Demonstrators slashed car tires and smashed trailer windows.
Police in riot gear faced off against the demonstrators, some of whom held up umbrellas against falling pellets of pepper spray.
The Seattle Times newspaper quoted police as saying 16 people were arrested on suspicion of assault against officers, obstruction and failure to disperse.
The latest spasm of violence came after police and federal agents fired tear gas and forcefully dispersed protesters further south in Portland early Saturday, also in anger over Trump's heavily-criticized "surge" of security forces.
The city, the biggest in the state of Oregon, has seen nightly protests against racism and police brutality for nearly two months, initially sparked by the death of unarmed African American George Floyd at the hands of police in Minnesota.
Portland is also a stage for the highly controversial crackdown by federal agents ordered by Trump -- one that is not supported by local officials there, and which many say smacks of authoritarianism.
Civil unrest was not only confined to Portland. On Saturday, three members of a black militia were shot in Louisville, Kentucky at a Black Lives Matter protest, local media reported, citing police. Their injuries were not life-threatening.
The protest, to demand justice for a black woman who was killed by police as she slept in her home, drew members of the black militia and a rival far-right militia, with the heavily armed groups facing off while separated by riot police.
The groups dispersed peacefully later Saturday afternoon.
In Portland, Friday's demonstration was mainly peaceful, with crowds playing music and dancing, blowing soap bubbles and setting off fireworks.
But it ended -- like many before it -- in a showdown between protesters and police, which escalated in a haze of tear gas and flashbang devices.
One group of protesters formed a line with umbrellas and makeshift shields to try to protect themselves, as at least two fires burned outside fences around a federal courthouse.
Tear gas was first fired around 11:00 pm. By 2:30 am police and federal agents were clearing the scene outside the courthouse with tear gas, pushing protesters back.
Earlier, protesters who spoke to AFP complained of the federal agents' presence in the city and voiced their support for the Black Lives Matter movement, which helped drive demonstrations across the country for weeks after Floyd's killing.
"I don't like what's happening down here, what Trump is doing," Mike Shikany, a 55-year-old aerospace engineer, said, adding he did not "want to get anywhere near the little green men," meaning the federal troops.
Portland retiree Jean Mullen, 74, said that without pressure nothing would change.
"It's time to become the country we always brag about being. And we can't brag anymore, about anything. We aren't first in anything and it's a terrible, terrible thing to see at the end of my life," she said.
The inspector general of the US Justice Department on Thursday opened an official investigation into the federal crackdown, but a federal judge in Oregon on Friday rejected a legal bid by the state to stop agents from detaining protesters.
Trump, who is campaigning for re-election in November on a platform of "law and order," announced on Wednesday a "surge" of federal agents to crime hotspots including Chicago, following an increase in violence in the nation's third-largest city.
Agents deployed there will partner with local law enforcement, not riot control forces as seen in Portland.
Local officials have warned they would draw the line at any Portland-style deployment.