More than 10,000 protesters converged on the US capital today to help draw attention to the deaths of unarmed black men at the hands of police and call for legislative action.
Led by several civil rights organisations, the crowd will march to the Capitol later with the families of Michael Brown and Eric Garner, two unarmed black men who died in incidents involving white police officers.
The Rev Al Sharpton, a prominent civil rights advocate, also will be part of the march.
The groups and marchers - with signs reading "Black Lives Matter" and "Who do you protect? Who do you serve" - are calling for law enforcement reforms after several high-profile cases of what they call police brutality.
At Freedom Plaza, the rally was interrupted briefly by a group of protesters who took the stage with a bullhorn. They announced that they were from Ferguson, Missouri - where Mr Brown died - and demanded to speak.
Rally organisers called the interruption unnecessarily divisive. Speakers were delayed about five minutes as supporters of the interruption chanted "Let them speak".
Protests - some violent - have occurred around the US since grand juries last month declined to indict the officers involved in the deaths of 18-year-old Mr Brown and 43-year-old Mr Garner, who gasped "I can't breathe" while being arrested for allegedly selling loose, untaxed cigarettes in New York. Some protesters held signs and wore shirts that said "I can't breathe" today.
Politicians and others have talked about the need for better police training, body cameras and changes in the grand jury process to restore faith in the legal system.
Terry Baisden, 52, of Baltimore, said she is "hopeful change is coming" and that the movement is not part of a fleeting flash of anger.
She said she has not protested before but felt compelled to because "changes in action, changes in belief, happen in numbers".
Murry Edwards said he made the trip to Washington from St Louis because he wants to make sure the momentum from the movement in Ferguson reaches a national stage.
"This is the national march," he said. "We have to get behind the national movement."
Today's march - sponsored in part by such civil rights organisations the National Action Network, the Urban League and the NAACP - is scheduled to go down Pennsylvania Avenue between the White House and the Capitol. At the Capitol, speakers will outline a legislative agenda they want Congress to pursue in relation to police killings.
While protesters rally in Washington, other groups including Ferguson Action will be conducting similar "Day of Resistance" movements all around the country. A large march is planned in New York City.