PORTLAND, ORE. -- The arrest during protests in Portland, Oregon, of a Black woman who became a leading activist in the racial justice movement after she was assaulted by a white supremacist three years ago has galvanized local and national Black Lives Matter groups.

More demonstrations were planned in the city Monday night. Portland has seen more than two months of often violent, nightly protests since George Floyd was killed in Minneapolis.

Authorities said Demetria Hester, 46, won't be charged following her arrest early Monday. Hester had been booked on suspicion of disorderly conduct and interfering with a police officer during the protest that began Sunday night. Hester's arrest drew a sharp rebuke from national Black Lives Matter activists, who are increasingly focusing on demonstrations in Oregon's largest city.

After her release, Hester said at a news conference that she would keep protesting and joined others in announcing plans for a fundraiser to send Black mothers to Washington, D.C.

"I was born and bred to do this. This is a dream come true," Hester said. "This is a revolution and we're getting reparations."

Hester and 15 other people were arrested during Portland's 73rd consecutive nights of protest. A group of about 200 demonstrators gathered at a park and then marched to the police union headquarters, where some people set fires outside the building and launched fireworks at officers.

Two officers were injured, including one who was burned on the neck when a firework exploded, police said.

Police declared a riot shortly after 10 p.m. and began arresting people, including Hester.

U.S. President Donald Trump once more seized on the protests and said on Twitter that Portland was "out of control." He urged Democratic Gov. Kate Brown to bring in the Oregon National Guard.

On Monday, civil rights groups in Portland and members of the international Black Lives Matter organization, who travelled to Portland, decried Hester's arrest and said the city was at the centre of the racial justice protest movement.

"The struggle here in Portland has become almost ground zero because what we've seen under this administration is the kind of flexing that we haven't really seen in our generation, ever," said Janaya Khan, co-founder of Black Lives Matter Toronto. "People only protest when politicians and policies and police have failed to protect them. "

Hester gained prominence in 2017 when she was assaulted by a white supremacist while riding a light-rail train. The man who attacked Hester, Jeremy Christian, stabbed two men to death the following night and critically injured a third man when they came to the defence of two Black women -- one of them wearing a Muslim head-covering -- who were being harassed by Christian.

Hester gave emotional testimony this spring at Christian's murder trial. Christian was convicted and given two life sentences without possibility of parole.

Hester has reappeared in public this summer as one of the main organizers of a group of mostly white parents who have been protesting nightly. She leads marches each night, using a bullhorn to chant in a voice cracking with fatigue.