Thousands of demonstrators streamed down Pennsylvania Avenue on Saturday, shouting “Black lives matter,” “Hands up, don’t shoot” and “I can’t breathe” to call attention to the recent deaths of unarmed African American men at the hands of police.

The peaceful civil rights march led by families of the slain and organized by the Rev. Al Sharpton’s National Action Network drew a wide range of Americans — black, white, Latino, Asian, young and elderly. They walked east toward the U.S. Capitol in a stream of colorful T-shirts, banners and signs.

The day’s most poignant moment came when a number of family members of black men and boys killed by police — Eric Garner, Michael Brown, John Crawford III, Tamar Rice and Amadou Diallo — took the stage at a rally at the Capitol.

“What a sea of people,” said Lesley McSpadden, the mother of Brown, an 18-year-old killed in Ferguson, Mo, in August. “Thank you for having my back.”

“This is a history-making moment,” said Garner’s mother, Gwen Carr. “We need to stand like this at all times.”

Bishop D. Demond Robinson and 25 residents of Ferguson took an 800-mile road trip from Missouri to Washington to march with other protesters from around the country in opposition of police brutality. (Whitney Leaming/The Washington Post)

“Let’s keep it strong, long and meaningful,” said Esaw Garner, the widow of Garner, who was killed by an officer in New York City in July.

Several protesters walked up to Michael Brown Sr., seeking hugs, handshakes or a picture. Brown tried to be accommodating to the many requests, at one point showing a young man how to take a selfie.

“This means the world to me, to see everyone coming together for a common cause,” Brown said.

But all did not go as planned, as a group of young demonstrators opposed to Sharpton, who they view as a celebrity activist seeking to take over a movement they started in Ferguson, seized the stage for a few minutes by shouting through a bullhorn. Many in the crowd frowned on the intrusion.

Photos, tweets and video from the crowd.

Protesters marched through downtown Washington to the Capitol Saturday in light of recent grand jury decisions regarding the killings of Michael Brown and Eric Garner by police. (The Washington Post)

When Sharpton took the stage at the Capitol, he urged the marchers not to let “provocateurs” divide them, by generation or race.

“This is not a black march or a white march,” Sharpton said. “This is an American march so the rights of all Americans are protected. I’m inspired when I see white kids holding up signs saying ‘Black Lives Matter.’”

Joe Madison, a satellite radio talk show host, echoed that theme. “This is not old versus young, black versus white,” he told demonstrators. “All human lives are important.” He said they were standing on the shoulders of leaders whose names became famous during the civil rights movement led by Dr. Martin Luther King a half century ago.

“You are the John Lewises. You are the Fannie Lou Hamers, “ Madison said.

“We are here because we refuse to accept injustice,” said Rep. Al Green (D-Texas), promising that Congress would pass legislation seeking better oversight of policing across the country.

As Sharpton took the podium, however, dozens and dozens of protesters walked west on Pennsylvania Ave, leaving the rally.

“We wanted to be here. This was wonderful. But we’re good,” says Kiesha Thomas, 32, of Chicago.

David Saunders, 62, was also leaving. “I believe in the march. But I don’t want to hear him.”

The Washington march was one of a wave of demonstrations across the nation. Separate marches were held from San Francisco to New York, including a Millions March and rally near New York University, and a demonstration before the nationally televised basketball game between two top teams, the universities of North Carolina and Kentucky.

Eents were as varied as the individuals organizing them, including, for example, a wilderness “healing hike” in hills outside Oakland, Calif.

Thousands of protesters crowded New York’s Fifth Avenue on Sunday for the first large-scale, organized protest in the city since a grand jury on Staten Island declined to indict a police officer for the death of Eric Garner.

The crowd reflected the diversity of the city, if not the high-income neighborhood in Manhattan’s West Village. “I’ve never seen something so beautiful,” said Josh Toney, an African-American man in his 20s. “Seeing the Asian community, seeing Union workers, seeing people who probably don’t even speak English.”

A number of members of Alpha Phi Alpha, an historically black fraternity, served as marshals. “We’re trying to bring awareness,” said Charles James II, of SUNY Old Westberg. The best outcome, he said, would be “changing the minds of the people we’re trying to reach.”

Sheldon Jackson, standing nearby, interjected. “Best outcome for who?” “What we need,” Jackson said, “is to have the police protect the community, not themselves. We’re paying for our own assassinations. They’re taxing the people to come back and exterminate us.”

“Take any young black boy and put a police officer in front of him, and he’ll be nervous,” Jackson said. James and William Douglas, another marshal, agreed. “It’s exhausting,” James said. “You can write that, too.”

By 11 a.m. Saturday in Washington, several thousand people were jammed into Freedom Plaza near the White House as the crowd chanted the names of those recently killed by police, and "No Justice, no peace!"

Some held signs with messages such as “Black Lives Matter," "Stop Killer Cops" and "Hands up Don't Shoot."

Beating drums and waving signs, thousands of marchers began to make their way down Pennsylvania Avenue to the Capitol. Various songs played over loud speaker as they marched — from Mahalia Jackson singing a hymn to Marvin Gaye’s “What’s Going On.”

James Teal, 50, of Arlington, said he showed up at starting point, at 7 a.m.

Shortly before 9, he stood bundled against the morning chill and holding an American flag upside down on its pole. The flag bore the names of slain black men and boys, including Emmett Till, the 14-year-old killed in Money, Miss., in 1955 and whose death helped ignite the civil rights movement. Other names included Amadou Diallo, Treyvon Martin, Tamir Rice, and Brown and Garner.

Teal said he had recently been arrested in Arlington for protesting on Columbia Pike.

“I’m here because police brutality, racial profiling, this just will not be tolerated. I hope people come today and go back home with the sense that what we really need to do is vote ,” he said.

“I got the flag upside down, not as showing disrespect for my country. I love my country. I also love the constitution more then this flag”

“The flag is just an upside down symbol of showing a sign of distress that this country and this nation is in,” he said

A group of Unitarian Universalists from the Washington area wore yellow T-shirts and carried a large yellow banner that said “Stand on the Side of Love.”

Eli Briggs, 44, of Silver Spring, a member of the Unitarian Universalist Church of Silver Spring, said she had come to “stand up for the ideals of justice for all people and that these killings of minority teenagers need to stop.”

“There’s a lot more that needs to happen in terms of racial justice but at a bare minimum we need to stop the killings,” she said.

“We would like the Department of Justice to look into some of these incidents and really take an objective view of what’s happening and how we can make it stop,” she said. “Mainly today is about bearing witness to what’s going on and saying it has to stop.”

Mikaela Seligman, 45, a non-profit consultant, was headed to Freedom Plaza with her husband, two sons, 2 and 6, and her mother.

“As a parent I struggle to think of ways to explain the conversation we are having with our kids. It’s important for them to see this,” she said.

“It’s also important that we’re white. This is not an issue just for black people, this is an issue for us as a nation,” she said.

In 1963 Bill Griffin was 13 years old and still in junior high school in Greensboro, N. C. His mother, father and older brother participated in the big Civil Rights marches, but they told him he was too young.

 Saturday, the 64-year-old retired math teacher from Harlem helped organize a busload of 55 demonstrators to attend Saturday's march.

"I couldn't participate then, but I can do something now," Griffin said.

On Thursday in Washington, black staffers on Capitol Hill stood on the steps of the Capitol in prayer and a silent protest, and Friday night members of churches and others lined 16th Street, from Silver Spring to the White House, in a candlight vigil.

The myriad demonstrations in recent weeks over race and police tactics are rooted in the Ferguson protests that began in August following Brown’s death. They grew significantly after a New York grand jury declined to indict an officer in Garner’s death. That decision came a week after a Missouri grand jury declined to indict in Brown’s shooting death. Garner’s altercation with police was caught on video, and the decision to file no charges drew outrage across the political spectrum, from liberals and conservatives alike.

Protests in what appears to be a burgeoning movement have been organic and original, and not surprisingly have shown generational fractures from its earliest days in Ferguson.

Those slain recently by police include Garner, a cigarette vendor killed July in a chokehold; Brown, who was shot in August; Tamir Rice, a 12-year-old from Ohio shot in November while holding a pellet gun; and John Crawford III, shot in August by police in an Ohio Wal-Mart.

Trayvon Martin, 17, was killed in 2012 during a confrontation with an armed neighborhood watch volunteer, who prosecutors initially chose not to charge, despite some questions surrounding the shooting.

Sharpton has said his work and his group offer support to grieving families, which often lack the resources that police have to control the public narrative.

“We’re like the union for families because they want an infrastructure to fight an infrastructure,” Sharpton said. “You can’t sit up in your living room and fight an institution unless you have institutional support.

“We do not want this to be an episodic movement,” he said. “We want it to be real change.”

Sharpton’s celebrity came through protest and fighting authorities for decades, ringing up victories and suffering embarrassing losses. He expanded his image by unsuccessfully campaigning for a Democratic presidential nomination in 2004.

His exposure caught the attention of African Americans such as Garner’s widow, Esaw Garner, and his mother, Gwen Carr; Brown’s parents, Michael Brown Sr. and Lesley McSpadden; Tamir’s mother, Samaria Rice; as well as Martin’s parents, Sybrina Fulton and Tracy Martin. Each is expected at the march backed by Sharpton.

But some young people have been blunt in their criticism. “I think part of it is people just don’t connect with his leadership,” said Charles Wade, co-founder of a group Operation Help or Hush, who plans to participate in the Millions March.

“This weekend, people were going to D.C., but they’re no longer going because there is a march by young people, organized by young people, that young people funded,” Wade said. “We’ve been excluded by the traditional groups, so we’ve started our own thing.”

Shermale Humphrey of St. Louis, who joined protests in Ferguson that started the day after Brown was shot, said she agrees with “a lot of what” Sharpton says, but not his constant presence as a major organizer.

“Why should it be that when something happens we should always see your face?” Humphrey said, referring to Sharpton. “We need older people, their wisdom, because younger people can wild out without guidance. But we need them all the time, not just when something happens.”

The Washington march will likely dwarf the others Saturday. Organizers said buses are coming from New York, New Jersey, Philadelphia, North Carolina, Florida and elsewhere. The march will be augmented by the presence of old-guard civil rights groups: the Black Women’s Round Table, the NAACP and the National Urban League, along with partners such as the American Civil Liberties Union.

On Friday night, a group of about 25 demonstrators arrived in Washington from Ferguson. Protesters from the D.C. area had gathered in front of the DoubleTree Hilton in Crystal City to greet them.

Bishop D. Demond Robinson of the Kingdom Destiny church brought three vans full of young adults and teenagers and a few middle-aged women.

Over a bullhorn, they told everyone to get as close to the stage as possible at the rally, and they vowed to take it over if they were denied a chance to have their say.

Michael E. Ruane, Mariam Baksh and Whitney Leaming in Washington and Philip Bump in New York contributed to this report.