As Aretha Douglas Wallace did her best to fight back tears, the proud but devastated mother described her 10-year son, Justin, with the highest praise.

“He was my pride, my joy, my everything — my world, my rock,” Wallace said.

The NYPD said Justin, who would have turned 11 on Tuesday, was shot and killed late Saturday night while visiting relatives on Beach 45th Street, about a mile away from where he lived.

Police say just after 9:30 p.m., Justin was shot in the torso by a person who fled the scene.

We’re also told a 29-year old man, who is believed to be Justin’s cousin, was shot multiple times in the shoulder and back, and is in stable condition.

Eight-year-old Isaiah Craig told NY1 Justin was not only his neighbor and schoolmate, he considered him his best friend.

“He usually made me laugh because of the way he used to talk to me about things,” Craig said through tears. “He was just the best person ever. And I miss him so much.”

Isaiah’s mom, Belinda, described Justin as the smartest kid she’s ever known, saying he helped Isaiah with homework and they’d sit together on the bus.

“Oh my God. It’s traumatic. He was like a son to me. He came over here every day,” Craig said. “We saw him yesterday outside next door and we wave and we said hi, and to wake up to this is just really bad and I’m heartbroken!”

Mayor Bill de Blasio himself got emotional when he described his half hour visit Sunday evening to Justin’s home.  He reassured the boy’s family of one thing.

“We’ll find this killer. We will find this killer. He will be punished. Period,” de Blasio said. “That’s what they want to know. Will this killer be found? Yes, and he will be punished.”

While police have not indicated a motive for the shooting, they did release surveillance video Sunday that shows a person of interest who investigators say fired numerous rounds before fleeing the scene.

Anyone with information is urged to call the Crimestoppers hotline at 1-800-577-TIPS.