Peaceful protests against police brutality and the presence of federal agents at demonstrations turned violent as police in several large cities across the country declared riots, and one protester in Austin was killed in a shooting that erupted during a weekend of civil unrest.
A Black Lives Matter protester was fatally shot just before 10 p.m. on Saturday during a march in downtown Austin, police said.
While police initially said the protester, identified as Garrett Foster, was armed when he approached a car occupied by a man who killed him, Foster's mother disputed the account during an interview Sunday on ABC's "Good Morning America."
Sheila Foster said her son was pushing his fiancee's wheelchair when he was gunned down.
"And this gentleman got out of his car and started firing shots, and my son was shot three times," the mother said.
The gunfire, which was captured on cellphone video, caused protesters to run and duck for cover.
Police said the suspected gunman was captured and was being interviewed by investigators. The alleged gunman's name has not been released.
The deadly violence occurred as protests across the country turned from peaceful to chaotic.
Police in Portland, Oregon, declared that a demonstration turned into a "riot" early Sunday when protesters breached a reinforced fence around the Mark O. Hatfield U.S. Courthouse in downtown Portland. Federal agents guarding the building deployed tear gas on the demonstrators, who officials alleged hurled projectiles and fireworks at the agents.
MORE: Federal officers clash with protesters in Portland as US attorney calls for investigationIt was the 59th straight day of protests in Portland and demonstrators have accused federal agents of inflaming violence by using questionable tactics for detaining protesters and dispersing crowds.
President Donald Trump has threatened to send federal agents to more cities to restore order.
More than 100 miles away in Eugene, Oregon, police also declared a "riot" when Black Lives Matter members, protesting in solidarity with their Portland counterparts, clashed with counterprotesters waving American flags and toting signs reading "All Lives Matter," according to police.
Police said they moved in to quell the demonstrations when vandalism occurred to businesses, including a Whole Foods store, and officers witnessed and arrested a man allegedly firing a gun into the air. Rocks and other objects were also thrown at police, officials said.
At least eight other people, including a juvenile, were arrested on suspicion of rioting in Eugene, police said.
In Oakland, California, a peaceful march through the city's streets intended to show support for the ongoing protests in Portland erupted in violence late Saturday.
The Oakland Police Department tweeted that some agitators among the roughly 700 peaceful demonstrators vandalized a police station by breaking windows, spray painting walls and shooting fireworks. Police officials said multiple small fires were set throughout the city, including one at the Alameda County Superior Courthouse.
Police said several arrests were made.
In Seattle, officials said that 59 police officers were hurt on Saturday in clashes with protesters and that 47 arrests were made.
Seattle Police Chief Carmen Best said at a late-night news conference Saturday that protests were mostly peaceful until nightfall when some agitators began throwing rocks and explosives at police. Best said one officer was hospitalized with a leg injury caused by an explosive.
Earlier in the day, a dozen people set fire to portable trailers during a protest at the construction site of the new King County Juvenile Detention Facility, police said. Officials also said that windows of cars and some businesses were broken near downtown Seattle as groups of protesters marched through the area.
Police said they were also investigating an explosion that damaged the facade of the police department's East Precinct.
"There, several people emerged from the group and began spray painting and attempting to disable security cameras and a fenced perimeter around the precinct. At least one person breached the precinct’s fence line. Moments later, a device exploded leaving an 8-inch hole in the side of the precinct," police said in a statement.
MORE: Riot declared in Portland, mayor in crowd as feds disperse tear gasBy 10 p.m. Saturday, police had made 45 arrests, officials said.
Meanwhile, the police department in Richmond, Virginia, declared an unlawful assembly on Saturday night after more violence erupted there.
MORE: Trump says 'a lot of people in jail' after Portland protests, but few were chargedA demonstration billed as "Richmond Stands with Portland" started out with a peaceful march but became unruly as marchers made their way to Richmond Police Headquarters, officials said.
Prior to reaching police headquarters, police said some in a group of mostly peaceful protesters set fires, broke windows and spray-painted graffiti on buildings. Some damage was done to buildings at Virginia Commonwealth University, police said.
Just after 11 p.m. Saturday, police tweeted “please disperse or face arrest” while addressing protesters outside police headquarters. Police posted on Twitter images of rocks, batteries and other projectiles they said were hurled at officers posted outside the headquarters that "prompted an Unlawful Assembly being declared."
A city dump truck parked near police headquarters was also set on fire, according to police.
The Virginia State Police said its troopers were helping to protect the police department headquarters when several people who were among the protesters tore down police tape and moved forward pointing lasers and shooting firecrackers.
Police said tear gas was used to disperse the crowd outside the headquarters.
Four men were arrested and charged with unlawful assembly, police said. A 29-year-old man Richmond man was also arrested and charged with rioting with a firearm, while a 28-year-old man from Hopewell, Virginia, was arrested on suspicion of assault on a law enforcement officer and rioting, according to police.
ABC News' Ahmad Hemingway and Alexandra Faul contributed to this report.