This de Blasio administration official set one heckuva bad example for the teens she was hired to keep out of jail.

Reagan Stevens, a deputy director in the Mayor’s Office of Criminal Justice, and two young men were arrested for illegal weapons possession while sitting in a double-parked car near the scene of a Saturday night shooting in Queens, cops said.

A loaded, 9mm semi-automatic pistol with its serial number defaced was hidden in the car’s glovebox, and there was a spent shell casing on the floor near Stevens’ feet in the rear of the 2002 dark red Infiniti SUV, law enforcement sources said.

The trio’s arrest followed a burst of five gunshots that activated an NYPD “ShotSpotter” device in Jamaica at 9:42 p.m. Saturday, sources said.

The listening device pinpointed the shooting at 174th Street and 109th Avenue, and private surveillance video captured the muzzle flashes of five shots fired from the Infiniti, sources said.

The handgun seized by cops has an eight-round magazine and held three cartridges — two in the magazine and one in the chamber, sources said.

Stevens, 42, and the two men — who cops say also had knives on them — were awaiting arraignment Sunday night in Queens Criminal Court, where her mom, Deborah Stevens Modica, has been a judge since her appointment in 1997.

Her stepdad, Salvatore Modica, is an acting Queens Supreme Court justice. They both declined to comment.

Stevens, who lives in Brooklyn’s Bay Ridge, manages youth and strategic initiatives, and her main job is implementing a 2017 state law that will raise the age at which kids can be prosecuted as adults for non-violent crimes from 16 to 18.

Stevens, who previously worked for the Brooklyn District Attorney’s Office and makes more than $90,000 a year, was immediately suspended without pay, said Office of Criminal Justice spokesman Patrick Gallahue.

“We take these allegations very seriously,” he added.

Mayor Bill de Blasio is an outspoken supporter of strict gun control laws, and last month, he joined a student walkout in the wake of the mass shooting that killed 17 students and staffers at a Parkland, Fla., high school.

Stevens was arrested around 10:25 p.m. near the corner of 177th Street and 106th Avenue along with driver Caesar Forbes, 25, and front-seat passenger Montel Hughes, 24, both of whom live in the neighborhood.

Hughes’ sister, Jade, 17, told The Post that her brother and Forbes were longtime friends and that he recently became acquainted with Stevens.

She said she didn’t know anything about that relationship other than that it wasn’t romantic.

Stevens, Hughes and Forbes were each charged with two counts of criminal possession of a weapon — one for the gun being loaded, another for its illegally obscured serial number — because no one admitted owning the pistol, sources said.

Cops were also weighing charges involving its firing, based on the video that traces the shots to the car, sources said.

Forbes and Hughes also were charged with criminal possession of a weapon related to the knives they allegedly were carrying, and Forbes was also ticketed for double parking, cops said.

Hughes’ rap sheet lists nine prior arrests, six of which are sealed. The others include an October 2010 bust in Queens on robbery and weapons charges, and a July 2016 arrest on firearm, trespassing and harassment charges, sources said.

Stevens has a sealed 2015 arrest that stemmed from allegations of driving illegally, while Forbes has no criminal record, sources said.

Stevens was released on her own recognizance, according to a spokeswoman for the Queens DA’s office. Meanwhile, Forbes was held on $3,500 bail or $7,500 bond, and Hughes was held on $10,000 bail or $20,000 bond. They are due back in court on April 24.

Additional reporting by Stephanie Pagones, Reuven Fenton and Yoav Gonen