Hundreds of protesters were arrested Thursday after staging a sit-in at a U.S. Senate office building in Washington to protest the Trump administration's immigration policy.

U.S. Capitol Police arrested 575 activists, mostly women, decrying President Donald Trump's "zero-tolerance" policy on admission of undocumented immigrants.

They chanted "What do we want? Free families!'' and "This is what democracy looks like,'' as they sat in the Hart Senate Office Building's atrium.

Protesters wrapped themselves in Mylar blankets, like the ones given to children separated from their families at the southern U.S. border and detained.

Democratic Senators Tammy Duckworth of Illinois, Maizi Hirono of Hawaii and Ed Markey of Massachusetts were among those who visited the protesters to lend their support.

Democratic Representative Pramila Jayapal of Washington, herself an immigrant, tweeted that she was among those arrested.

Under the zero-tolerance policy, the government has begun prosecuting all migrants caught entering the country without authorization. Trump has halted his policy of taking children from their detained parents under public pressure, but an estimated 2,000 of them are still being held, with many families saying they don't know how to locate them.

Similar protests also took place elsewhere around the country. Hundreds gathered at a rally outside a federal courthouse in Brownsville, Texas, near the U.S.-Mexico border in the Rio Grande Valley.

Dozens of people shut down a government meeting in Michigan to protest a contract with Immigration and Customs Enforcement to house detainees at a local jail. (VOA)

•Women hold signs as they protest the separation of immigrant families, June 28, 2018, inside the Hart Senate Office Building on Capitol Hill in Washington.