Police in Portland, Oregon have arrested fifteen suspects after a mob of around 200 alleged Antifa members smashed up the Democrat headquarters and federal immigration offices in the city on Wedensday, while three people were arrested after a crowd in Seattle attacked buildings and burnt a US flag.
The two Pacific Northwest cities have been hotspots for protests and violence since the Black Lives Matter demonstrations began last year in the aftermath of the death of George Floyd.
There were also protests in Denver, Colorado; Columbus, Ohio and Sacramento in California.
Portland Police released photographs of eight of the 15 arrested suspects as well as images of confiscated items including knives, batons and bullet-proof vests.
"Some of the crowd had pepperball guns, electronic control weapons, large fireworks, shields and rocks," said Portland police spokesman Kevin Allen.
Federal police, who were initially deployed to the city during the Black Lives Matter protests, were reported to have used tear gas, stun grenades and other non-lethal munitions to disperse the crowd.
The Federal Immigration and Customs Enforcement building that the rioters attacked had been a target during previous bouts of violence last year. Demonstrators have demanded that ICE, which enforces immigration law, be abolished.
Police did not comment on the political nature of the crowd, but the violence came on a day when several far-left demonstrations were planned to put pressure on the new Biden administration to swiftly introduce immigration, racial justice and policing reforms.
According to the Daily Mail, seven of the 15 suspects detained in Portland had been arrested at previous Antifa protests, while The New York Times reported that one flier handed out at the Seattle demonstration attacked Biden over "his stupid" crime bill passed in 1994, which was blamed for leading to mass incarcerations.
The Portland group was also reported to be carrying a banner reading: "We don't want Biden - we want revenge!" and to have chanted "---- Biden"
The Democratic Party of Oregon said in a statement to AFP that it was "frustrated and disappointed" by the damage to its offices - which were empty - but would not be deterred "from our important work."