The presidential campaign of Democratic candidate Bernie Sanders has apologized for ejecting members of a pro-Palestinian student group from a rally in Boston.

Members of the Boston Students for Justice in Palestine appeared Saturday night at a large Boston rally for Sanders at the Boston Convention and Exhibition Center. They stood in the overflow area, where the speech was being broadcast on a large screen, holding a sign reading: “Will Ya #Feel The Bern 4 Palestine??!”

The group said they were approached by police and venue staff and told that the Bernie Sanders’ campaign team asked them to take down the sign, according to an account posted on the group’s Facebook page. Police then told them they were trespassing and threatened them with arrest if they did not leave the venue.

“We understand we may have asked a tough question for Bernie’s campaign. However, what concerns us most about being unwelcome in this political space on the basis of a sign is not what is says about Bernie’s stance on Palestine, but rather, his team’s refusal to entertain diverse viewpoints,” the post said.

The group also posted a video on YouTube of the activists’ ejection from the venue.

Jeff Weaver, Sanders’s campaign manager, told the Washington Post on Monday that the instructions to take down the sign came from a “rogue” low-level campaign employee.

“That person has been excluded from working on any of our future events,” Weaver said. He also said that the campaign called and apologized to the student group.