WASHINGTON - Several hundred activists occupied a US Senate office building on Thursday, filling it with chants decrying US President Donald Trump's "zero tolerance" stance on illegal immigration before lining up to be arrested for refusing police orders to leave.The protesters, mostly women dressed in white, sat on the Hart Senate Office Building's marbled floors and wrapped themselves in metallic silver blankets. The blankets appeared to be a reference to those given to migrant children sleeping on thin mattresses on the floors of detention centers."Say it loud, say it clear, immigrants are welcome here," the crowd of about 500 protesters chanted."This is your final warning," a member of the Capitol Police told the protesters. "If you don't want to be arrested you need to leave."Police made protesters line up against a wall in small groups, and confiscated their blankets and signs before arresting them as other protesters cheered. Scores of Senate staff filled the upper mezzanine floors, staring at the commotion below.Democratic senators Mazie Hirono, Kirsten Gillibrand and Jeff Merkley and Congresswoman Pramila Jayapal, who have been critical of Trump's immigration policies, walked past police and chatted with some of the women. Gillibrand held up a sign that read: "End Detentions Now."Women's March, a movement that began in the United States when Trump was inaugurated in 2017 and expanded internationally, had called on women to risk arrest at Thursday's protest.Before arriving at Capitol Hill, the protesters marched down Pennsylvania Avenue, pausing to chant "Shame! Shame! Shame!" at the Trump International Hotel.The Women's March demonstration is part of a wave of actions against Trump, whose administration began seeking in May to prosecute all adults who cross the border without authorization.More than 2,000 children who arrived illegally in the United States with adult relatives were separated from them and placed in detention facilities or with foster families around the United States.The policy has led to intense criticism in the United States and abroad, so much so that Trump signed an executive order that would let children stay with their parents as they moved through the legal system.Loretta Fudoli took a bus to Washington from Conway, Arkansas, to join Thursday's protest. She said she had been arrested at demonstrations three or four times since she became politically active after Trump's election."Their parents shouldn't even be locked up," Fudoli said. "This is not a bad enough crime to lock them up and take their children away."Most of the children separated from their families before the order was signed have not yet been reunited with them.The White House has said that the order was not a long-term solution and has called for Congress to pass immigration reform.Larger protests are being planned for Saturday in Washington, D.C., and cities around the country under the banner of #FamiliesBelongTogether.