The organizers set up camp in front of the Metropolitan Detention Center, shining lights into the building to make contact with those detained inside while also singing songs about unity.
"We as Angelenos feel like a lot of the moves that have been made by federal immigration policy are super inhumane and we are taking a stand tonight," Ground Game L.A. organizer Meghan Choi said.
Earlier in the evening, protesters made their way into the loading dock area of the detention center before being pushed back by police.
Downtown LA crowd protests immigration policies
Recent images from the border and child detention centers across the nation have sparked visceral reactions over the last few weeks.
"I've been crying almost every night when I've been seeing the photos," West L.A. resident Kim Richter said. "My daughter is about that same age and I just thought it was so deeply cruel and inhumane."
But while this latest round of images has gotten a lot of attention, immigration activists note that these aren't new problems.
"What we have right now is utterly unacceptable, but it has been happening for a very long time," Choi said.