They're calling for an end to the president's immigration policy.
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"This is about black people, white people, Asian people, red people, everybody coming together for one bigger cause and that's us, that's our equality," said one activist.
This group is protesting President Trump's zero tolerance policy on immigration. "It's a zero humanity policy," activist Olga Talamente said. She wants the policy to end.
The sheriff's department posted several patrol cars, barricading the front door. A spokesman said it was a precaution.
There were some tense moments when a man told the crowd he had been incarcerated inside the jail facility and conditions were good, he also said ICE was doing "good work."
The man was shouted down and escorted away by sheriff's deputies.
"People who are coming to seek asylum have the legal right to be here," Talamente said.
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This group says it's not encouraged by the president's recent move to end its practice of separating migrant families. "Supposedly now, the children will be with families but they can detain them indefinitely," Talamente said.
Hilltop Community Council's Cesar Zepada said, "It's no longer personally affecting me, but it's affecting the community, it's affecting the families that are coming in trying to look for better opportunities."
The protest was held outside the West County Detention Facility, where undocumented immigrants have been detained by ICE.
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"The county has a contract with ICE, and our community doesn't want that," Kimberly Aceves-Iniguez said.
Contra Costa County sheriff's deputies barricaded the front doors to the detention facility with their patrol cars. A sheriff's spokesperson says it's a precaution to allow regular businesses to be conducted at the jail.
The Contra Costa Couty sheriff says local, state and federal officials have toured this facility in the past and also says that detainees are treated well and are offered services and assistance when they need it.
The protest is scheduled to last until 7 p.m.
For more on the Crisis at the Border, visit this page.