Dozens camped in front of the U.S. Immigration & Customs Enforcement building in the city's Financial District. They've blocked entrances on both Washington and Jackson streets.
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Instead of celebrating the Fourth of July in the traditional sense, they're holding a "Block ICE" block party. Organizers call it a celebration of resistance.
Protesters have encamped at ICE buildings across the country, following a weekend of marches in reaction to the administration's family separation policy.
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San Francisco's encampment started Monday with a rally held Tuesday afternoon.
"We are united under the banner of the destruction of ICE, wholesale, and the humane treatment of people who are trying to come into this country whether or not they have documentation or not," said Zoe Samudzi at Tuesday's rally.
The protest has not interrupted or changed court operations so far, according to a court spokesman.
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He says many of the people appearing don't physically come to the courthouse.
"They appear via video link between our court and that detention center, so protesters outside aren't going to keep them from getting to the courtroom," said Ken Gardner, Public Information Officer (Western States) for the Executive Office for Immigration Review.
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Federal offices are closed for the Fourth of July holiday.
President Donald Trump had this to say about ICE on Tuesday, "We're not abandoning ICE and we're not abandoning our law enforcement."
The Block ICE block party begins at 12 p.m. Organizers are asking for supplies and for supporters to join them.
For more on the ongoing border crisis, visit this page.