The largest demonstration on Thursday saw the 90-ft atrium of the Senate Hart Office building overrun by hundreds of women who sat on the floor pumping their fists in the air.
Three U.S. congressmen were arrested previous year for protesting President Trump's immigration policies, according to the Los Angeles Times.
"It means the clock is ticking for the Trump administration and they need to show how they're going about reuniting these families", said Jess Morales Rocketto, political director at the National Domestic Workers Alliance.
Protesters at the sit-in also chanted "We care!" in a likely nod to the olive-green jacket worn by first lady Melania Trump on the flight to visit children at the border last week, which said on the back "I really don't care, do u?" Mr. Trump signed an executive order ending family separations, but hundreds of children remain separated. Protesters will march in a circle around the Department of Justice building before dispersing.
The number of rallies, protests and marches planned for Saturday to protest the Trump administration's immigration policies has expanded to more than 700 nationwide, organizers said.More news: MI Muslims Rally Against Supreme Court Travel Ban Decision
She added that she was proud to have been arrested among hundreds of others who believed that "the United States is better and as a member of Congress I refuse to let this president and administration do what they are doing to children in my name".
The women chanted slogans such as "we care" and "where are the children" in a largely peaceful standoff with police, who ordered them to leave.
"People across my state of NY, all across the country are furious with this administration's policy to separate children from their parents", Sen.
She later tweeted out another video after her arrest. "Our fight won't end until all mothers are reunited with their children, which is why we are demanding an end to immigrant detention once and for all".
A longtime immigration-rights leader who founded OneAmerica before running for elected office, Jayapal said she has been outraged and unable to sleep over Trump's "zero tolerance" prosecutions of people crossing the US-Mexico border, The Seattle Times reported. They were charged with unlawfully demonstrating, a misdemeanor. "I don't think it's just part of the "resistance" energy we've seen since the election", Morales Rocketto said.