Elite NYPD officers from the Emergency Services Unit (ESU) were forced to spend Wednesday morning inspecting and dismantling guerrilla art installations around the city depicting children confined in metal cages — and department insiders were furious the officers were diverted from more important duties.

At least 18 identical installations — a commentary on the Mexican border crisis — popped up in the wee hours at prominent locations across Manhattan and Brooklyn, including the Barclays Center, Mayor Bill de Blasio’s Park Slope YMCA and the offices of several news outlets, police sources told the New York Post.

“It was a waste of time and resources,” fumed one high-ranking source, explaining that police had to use an abundance of caution to make sure the cages weren’t rigged with explosives. “ESU had to go to every one of them to make sure they weren’t dangerous."

The source added: “We want to talk to whoever did this.”

The NYPD said no one had claimed responsibility for the pieces, but a Twitter account first used around 6:45 a.m. Wednesday, @NoKidsInCagesUS, posted several photos of the cages around New York.