(CBS) — A 9-year-old boy was fatally shot Monday afternoon in the Gresham neighborhood, and police implored the community to help identify those responsible.

Police say the victim was found fatally wounded in an alley near 80th and Damen around 4:15 p.m. He had been shot multiple times in the upper body.

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Shortly before the shooting, a number individuals were in the alley, and an argument or altercation occurred, followed by several shots, said Dean Andrews, the Chicago Police Department’s chief of detectives. Members of the group fled, he said.

“At this point it is unclear if this was a targeted incident or a tragic case of being at the wrong place at the wrong time,” Andrews told reporters. “At this time, we do not have a concrete motive, but we will be working around the clock to find out more.”

Family members identified the victim as Tyshawn Lee. They described him as a nice child who liked to play ball and video games.

Tyshawn’s aunt, Sabrina Lee, told CBS 2’s Susanna Song: “My last memory with him was on Saturday, when I took him trick or treating.”

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He was dressed as Batman. His basketball, which family said he took everywhere, was found near his body.

Police were canvassing the neighborhood to find witnesses or track down surveillance video that might help solve the crime, he said. Anyone with information is urged to call Area South dectives at (312) 747-8271.

A reward of $20,000 — part of it offered up by St. Sabina Church — has been offered to help track down the killer or killers.

“That’s not an accident, that’s not a stray bullet — that’s like an execution,” St. Sabina Pastor Michael Pfleger said.

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Tyshawn Lee, 9, was fatally shot in the Gresham neighborhood. (courtesy: Karla Lee)

Tyshawn Lee, 9, was fatally shot in the Gresham neighborhood. (courtesy: Karla Lee)