(CNN)Protesters marched again Saturday in cities nationwide to decry police brutality after the killing of two African-American men by police this week.
Black Lives Matter protesters return to the streets
While many were peaceful, events turned ugly in St. Paul, Minnesota, where protesters clashed with police on Interstate 94.
At least two officers were injured by protesters -- one hit with a glass bottle and the other by fireworks, according to St. Paul police.
Police used crowd control measures including smoke, police spokesman Steve Linders said.
Parts of the freeway are closed after as many as 200 people forced their way past Minnesota state patrol troopers who were trying to block them from getting on the road.
In Washington, a group marched peacefully through downtown Saturday night, chanting, "We young. We strong. We marching all night on." They temporarily shut down Rock Creek Parkway.
About 400 people covered a city block as marchers moved across a large area of northwest Washington and headed toward the Georgetown neighborhood late in the night.
It was the third night of marches in Washington.
Marchers included a mixed-race couple carrying a sign that said, "Injustice anywhere threatens justice everywhere," and a little girl with her parents, wearing a white tank-top with the words "My life matters" written on it in marker.
Eugene Puryear, the march organizer, said the shooting of five police officers in Dallas on Thursday was tragic but inevitable because of police violence against African-Americans.
"We're at a tipping point," he said.
In Atlanta, a group of protesters confronted police over Interstates 75 and 85, then moved into the Midtown business district.
Friday night, a large group that included rapper T.I. blocked a downtown Atlanta Interstate ramp.
Marchers also took to the streets Saturday night in Miami, with police saying Interstate 395 was shut down for a brief period. A reporter for CNN affiliate WPLG tweeted that demonstrators had blocked a major thoroughfare.
In Fort Lauderdale, Florida, a large group of Black Lives Matter supporters walked to the Broward County Courthouse and then the county jail, where prisoners heard their shouts and tapped on windows in response, WPLG reported.
The protests erupted initially after videos surfaced showing fatal police encounters with two black men, Alton Sterling and Philando Castile, in Louisiana and Minnesota, respectively.
Their deaths -- along with those of several African-Americans before them -- spurred anger and debate over the use of force by police and questions over racial profiling.
The protests came after a sniper killed five police officers during a demonstration in Dallas on Thursday.
Black Lives Matter condemned the Dallas attack, calling it a tragedy not just for those affected but also for the nation.
"Black activists have raised the call for an end to violence, not an escalation of it. (Thursday's) attack was the result of the actions of a lone gunman," the group said in a statement on its website. "To assign the actions of one person to an entire movement is dangerous and irresponsible. We continue our efforts to bring about a better world for all of us."