Update: The head of the Secret Service has called the organizers and apologized, saying the agency didn’t handle the situation well, the Washington Post reported.

Original:

Leave it to the Secret Service to rain on sick children’s parade. And by parade, we mean cancer vigil.

The Secret Service and the Park Police kicked out hundreds of kids and their families from Lafayette Park Saturday night as a result of security precautions, The Washington Post reports. They were there to attend a candlelight vigil in front of the White House to raise awareness for childhood cancer, an event that was planned and permitted for 7 p.m.-9 p.m., as part of the weekend’s CureFest for Childhood Cancer. People had already begun setting up their blankets and listening to the welcome music when they were told they had to leave.

The calm crowd (as one parent put it: “At first, we were patient. I mean we’re a peaceful community; we’re fighting for kids’ lives”) waited around for them to unlock the gates for several hours before giving up at 10:30 p.m. When some parents asked what was going on, officers on the scene cited President Barack Obama’s departure for the Congressional Black Caucus Foundation’s annual gala.

“We ended up waiting at the gates for two hours, and they never let us in,” Natasha Gould, an 11-year-old who has an inoperable brain tumor, told the Post. “I cried last night in my hotel room because it was my first CureFest, and I couldn’t believe people were acting like they don’t care about children.”

A Secret Service spokesman apologized for “not communicating more effectively” to the group.

To give some context: this is what the event looked like last year.