(Reuters) - A crowd of several hundred anti-racism protesters in Portland, Oregon, some of whom set a fire and launched fireworks around the U.S. courthouse, mostly dispersed early on Thursday, police said after declaring the gathering a riot and firing tear gas at them.
Several arrests were made after street confrontations began on Wednesday night when the crowd blocked traffic for several hours and some protesters launched commercial grade fireworks and threw rocks and eggs, police said.
"We know there are people in the crowd who do not want violence or vandalism to occur but know there are some people in this crowd who are engaged in criminal activity," Portland police said in a statement.
"Most of these people were seen wearing helmets, gas masks, and carrying shields and batons," it added.
Anti-racism protests in Portland and several other cities have at times erupted into arson and violence, and federal officers sent into the Northwest U.S. city have repeatedly clashed with crowds targeting the federal courthouse there.
The crowd that converged Wednesday night outside the courthouse building was asked to leave the area immediately, the police said, or be subject to tear gas, other crowd control agents, citation or arrest.
After a number of warnings, and confrontations with police, the crowd mostly dispersed by 2:30 a.m. PDT (0930 GMT), they said.
The courthouse has been the target of previous attacks by demonstrators in Portland as groups have gathered to speak out against racism and police brutality following the May 25 death of George Floyd.
Floyd, a 46-year-old African-American man, died after a white police officer knelt on his neck for nearly nine minutes.
U.S. Attorney General William Barr came under fire from Democratic lawmakers earlier this month for sending federal officers to disperse the protesters in Portland.
(Reporting by Peter Szekely in New York and Aishwarya Nair in Bengaluru; Editing by William Maclean and Dan Grebler)