The homeless shelter that housed four young men accused in a gang sex assault on a Queens churchgoer opened last year without any notice to the neighborhood — because “confidentiality and privacy are important” to the program, City Hall said Monday.

Residents near the 21-bed facility in Jamaica were furious to learn it was operating under their noses and blasted officials for not alerting them, with one saying, “The city should put a sign there.”

“It’s not safe for the community not to know,” added Josephine Alarcon, a stay-at-home mother of three who lives a block away.

Meanwhile, the NYPD released a photo of suspect Isaiah Shorter, 20, who remained at large following the arrests of three fellow shelter residents last week.

Law-enforcement sources said Shorter has 14 prior arrests, including two for robbery and one for endangering the welfare of a child, with a source saying he allegedly beat up the mother of his child in front of their baby.

Authorities say Shorter, Justin Williams, 17, and Brandon Walker, 20, accosted the 50-year-old victim, who had just left her Jamaica church, and forced her to perform oral sex on them at gunpoint.

Julisses Ginel, 19, is accused of threatening her, saying she would get shot if she didn’t comply.

Mayor de Blasio pleaded ignorance on Monday when asked about the community outrage over the homeless shelter, which serves youths ages 16 to 21 and is about a half-mile from where the assault occurred.

“I don’t know enough about the history of what the notification process is. I also don’t know what the laws governing it are because they are minors,” he said.