Dreamforce, Salesforce’s big annual conference in San Francisco, received quite a welcome on its first day as protesters converged on Moscone Center with a 14-foot-tall cage meant to depict the Trump administration’s detaining of migrant children and families.

More than a couple of dozen protesters walked with the red metal cage, which had signs affixed to it that read “Detention center, powered by Salesforce,” and “Locking thousands of children away, powered by Salesforce.”

Activists have been urging Salesforce, the San Francisco cloud company, to cancel its contract with U.S. Customs and Border Protection. The company has said it does not believe its technology is being used to help President Donald Trump’s administration detain migrants at the U.S.-Mexico border.

“We respect the right to peaceful protest,” a Salesforce spokeswoman said Tuesday. She referred to Salesforce CEO Marc Benioff’s tweets from over the summer, in which he said he had discussed the issue with his employees, hundreds of whom had signed a letter urging their company to cancel its government contract.

“Salesforce doesn’t work with CBP regarding separation of families at the border,” Benioff tweeted in July. “We don’t have an agreement with ICE.”

But advocacy groups are keeping the pressure on Benioff and co-CEO Keith Block. They include Color of Change, Demand Progress and RAICES, a Texas-based nonprofit that has been helping reunite separated families. In July, RAICES refused a $250,000 donation from Salesforce.

“Big tech companies like Salesforce are helping agencies like ICE and CBP make it easier to spy on, target, and strip people of their human rights,” said Jelani Drew, a campaigner for Fight for the Future, in a statement. Drew said there were about 30 people at the protest Tuesday.

The “detention cage” made its first appearance at Burning Man, protest organizers said. At its Dreamforce appearance, a couple of protesters were inside its walls as it rolled along. Some protesters also drove a 20-foot-long mobile billboard that read “Salesforce is helping Border Patrol violate human rights.”

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Salesforce workers demand company stop working for U.S. border agency: report Dreamforce usually draws more than 100,000 attendees a year, and the advocacy groups had urged a boycott of the conference, including by speakers such as U.S. Vice President Al Gore and Warriors star Andre Iguodala.

The U.S. government’s latest numbers, released Sept. 20, say that of the 2,654 migrant children separated from their parents, 2,151 have been discharged — meaning they were either reunited with their parents or released to others’ custody, PBS NewsHour reported. The government said it still had 182 children in custody who were covered under a lawsuit brought by the ACLU challenging the detention policy, while an additional 220 children are in U.S. custody but not part of the lawsuit.