Principal Julie Zuckerman strummed a guitar Tuesday afternoon, leading roughly 50 people to “This Land Is Your Land” outside Castle Bridge School in Washington Heights.

As a few children played on the fringes of the circle, parents, community members, and immigration advocates held a musical rally of sorts to symbolize their solidarity, less than a week after U.S. Customs and Border Protection agents parked a marked truck on a sidewalk outside the school.

The agents reportedly were just eating lunch in the area, but the truck’s presence and the agents’ parking job sent the immigrant-rich community on edge, as the rhetoric around immigration continues to stoke fear in certain areas. It caught the attention of City Councilman Ydanis Rodriguez and Chancellor Richard Carranza, who said the education department would speak with the Mayor’s Office of Immigrant Affairs to ensure incidents like this don’t happen again.

As the crowd sang outside Castle Bridge, they clutched painted signs that read “Families Belong Together,” “Stop Separating Families,” and “Keep Families Together.”

“Right now there are parents working hard to come up with a plan, so that if we get word that any agency is coming with the intention of separating families, that we have a plan to support each other,” Omar Freilla, a father of two young students at the school, told the crowd, who repeated his words back to him, phrase by phrase.

“And for some of us, that may be putting ourselves between federal agents and families,” Freilla said. “And we have to be ready for that because we have to support each other.”

The rally was conceived the morning after the truck incident, Freilla said. Parents met with Zuckerman and pretty quickly expressed an interest to hold a rally and have a session to educate parents on their rights if approached by immigration officials, he said.

Seventy percent of students at Castle Bridge are Hispanic, in a community that has many immigrant families. Tuesday’s crowd later filed into the school, where they attended a training hosted by the Northern Manhattan Coalition for Immigrants Rights, according to Freilla.

Laurie Wen, a member of Rise and Resist, an activist group that has opposed the Trump administration, does not have a child at Castle Bridge but attended out of solidarity. It’s rallies like this one, along with behind-the-scenes work by groups like hers, that drive change, she said.

Freilla said he’d heard the agents couldn’t find a place to park their large trucks, and Zuckerman said the agents left after she and the principal of P. S. 128, a second school that occupies the same building, asked them to leave.

Zuckerman said she received a call last Friday from the assistant commissioner of public affairs at Customs and Border Patrol, apologizing for what happened.

Freilla, however, remained concerned, saying parking spots are usually available on the street, and felt agents chose to park on a sidewalk near where parents typically pick up their children. (The officials arrived close to dismissal time.) “This was Customs and Border Patrol testing the waters,” he said.

Zuckerman said the assistant commissioner offered to host an assembly at the school with parents and students so he could explain that the community should not be afraid of the agency’s officials. She said they’re figuring out steps for an initial meeting with school staff.

“What I’m hoping is that families who feel most vulnerable know that there are things that they can do to reduce their vulnerability, and the rest of us in schools are behind them and with them in this,” Zuckerman said.