But an employee at the store, Zack Kassim, 19, said that Bunkless and two friends had entered the store on Sunday night and immediately started shoving cakes, candies and sodas into their pockets. Mr. Kassim said that when he yelled at the boys they ran behind the cash register and one of them slashed him with a box cutter.

Image William Bovian, standing, at home after his brother was injured. Bunkless Bovians basketball coach is seated at left. Credit... Tyler Hicks/The New York Times

“They were trying to rob us,” Mr. Kassim said on Monday, displaying cuts on his left wrist and forearm. “They weren’t playing around. If it was outside, in the store, it would be different. But when they came behind the counter it was something else.”

Family members described Bunkless, who lives in a public-housing project near the store, as an avid basketball player with a dresser full of trophies to prove it. He has three brothers and four sisters and attends Intermediate School 323, his family said. They said he was known as Bullaboo.

While his relatives said he was leader to his teammates on the court and a good friend to them when they were not playing ball, some neighbors at the Howard Houses said he was a source of irritation and harassment to the employees at Munchies Grocery.

Marilyn Quintana, a neighbor, said her 10-year-old son, Raul, was in the store when the fight took place. She said Raul left his money and a sandwich on the counter and ran home to tell his older brother, Bryan, that one of his friends had been badly hurt.