(CNN) - Lena Dunham, Sia, Amber Heard and other stars visited the border city of Tornillo, Texas, on Sunday to protest the Trump administration's policy that separated migrant children from their parents.
On Instagram, Dunham posted a photo of a number of celebrities in Tornillo holding protest signs in the Texas heat.
"We came to Tornillo, Texas, to show our solidarity with the families who have been separated, the children who are alone and the parents who are grieving and the undocumented Americans who are losing more than I can fathom," Dunham wrote. "Thank you, Tornillo, for showing us a warm border welcome and reminding us that together we rise."
The protest comes amid outrage over immigrant family separations, a consequence of the Trump administration's zero tolerance policy toward illegal border crossings. Amid photos and audio of separated children and a critical outcry, President Donald Trump signed an executive order on Wednesday that he said would keep migrant parents and children together, although it's legality is not yet clear.
More than 2,000 children remain separated from their families and in the custody of Health and Human Services, the White House said on Saturday. The administration has released a preliminary plan to reunite those children with their parents, but the details remain unresolved.
Tornillo is the site of a US-Mexico border checkpoint and a temporary shelter for unaccompanied migrant minors.
Other cities along the border have also been the site of protests. In McAllen, Texas, protesters briefly blocked a bus leaving a migrant detention center on Saturday.
Dunham was joined in the Tornillo protest by prominent politicians and cultural figures as well as regular citizens hoping to make their voices heard.
Former Secretary of Housing and Urban Development Julian Castro called on Trump to reunite children with their families immediately.
"This President and his administration -- they use cruelty as a hobby, incompetence is their standard operating procedure, division is their tool, and we cannot leave it to chance," he said to a crowd of protesters. "We need to verify that these children are being reunited with their parents."
Actress Amber Heard posted a photo to Instagram from the Tornillo Port of Entry. In the photo, she holds a sign reading: "Apartheid was legal. Holocaust was legal. Legality is a matter of power, not justice."
Sia, the singer, asked her followers to donate to Voto Latino, a political nonprofit aiming to get Hispanic voters to the polls, and said she would match all donations up to $100,000.
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