CHICAGO (CBS) — Bulls forward Taj Gibson’s 6-year-old cousin was stabbed to death Sunday night in an elevator at a public housing development in Brooklyn.

CBS New York reports Prince Joshua “P.J.” Avitto and 7-year-old Mikayla Capers were stabbed inside an elevator at the Boulevard Houses public housing development around 6 p.m. Sunday. Mikayla survived, but P.J. died of his wounds.

In a tweet about his cousin’s death, Gibson called P.J. “my lil super man” and noted his cousin was only two weeks shy of his 7th birthday.

Neighbors and family said P.J. and Mikayla were headed inside to get a snack when they were attacked.

“They were just going inside to get ices, that’s it, they weren’t bothering anybody,” Sophia Diaz said.

Mikayla, who was in critical condition late Monday, was able to give police enough of a description of the suspect to create a sketch.

Police said they are searching for a heavyset, male suspect in his 20s. He was apparently wearing a grey sweatshirt.

“He was last seen running eastbound through the development. We did recover a knife in the vicinity of 857 Schenck Avenue,” Chief of Brooklyn Detectives, Patrick Conry said.

Police were looking into whether the two young children were victims of a serial stabber, and said Monday evening that the stabbing might be related to an earlier incident due to “several common factors.”

Investigators found an 8-inch kitchen knife with a black handle near the scene — similar to one used in an attack Friday night just blocks away.

“We have all department resources focused on that particular area; very concerned about it,” said NYPD Chief of Detectives Robert Boyce. “We have re-canvasses – we canvassed last night; we re-canvassed today.

Mikayla’s great-grandmother Regenia Trevathan said, just before 6 p.m. Sunday, adults were watching the kids play outside on a playground on a picture-perfect Sunday evening, when the children went into the building for a snack. But horror awaited them in the elevator.

Police said a man cornered the two best friends in the tiny elevator and stabbed each child repeatedly. P.J. stumbled off at the fourth floor.

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