Residents of Newtown, Connecticut, site of a mass school shooting that reignited the US gun violence debate, participated in a Washington march for gun control with activists, politicians and actors.
Thousands of protesters were expected for the rally on Saturday on the National Mall, part of about a dozen across the United States in favour of gun control, organisers said in a statement.
Demonstrators began gathering at the Capitol Reflecting Pool and marched to Constitution Avenue toward the Washington Monument at 11am.
A rally took place near the monument just before noon.
Molly Smith, artistic director of Washington's Arena Stage, and her partner who organised the march were motivated by the December 14 massacre that killed 20 first-graders and six adults at Sandy Hook Elementary School in Newtown.
Politicians from Maryland and the District of Columbia, including Washington Mayor Vincent Gray, were scheduled to speak.
The march comes a week after gun rights supporters held rallies across the country to oppose firearms control.
The Newtown massacre has galvanised the US debate on guns and spurred President Barack Obama to propose the most significant gun-control steps in decades.
Obama wants to revive a ban on military-style assault weapons, a proposal that faces a tough battle in Congress.
He also wants to put in place mandatory background checks for all gun buyers, a step viewed as having a better chance of success.
Gun ownership rights are enshrined in the US Constitution.
They are closely guarded by gun advocates, such as the National Rifle Association.
About 11,100 Americans died in gun-related killings in 2011, according to preliminary data from the US Centers for Disease Control and Prevention.
There were 19,766 suicides by firearms in 2011, the CDC said.
The Washington rally is co-sponsored by One Million Moms for Gun Control, which is organising about a dozen similar events in cities that include San Francisco and Austin, Texas.