A 13-year-old Chicago boy who appeared in an award-winning public service video about the effect of gun violence on the city’s black youth was shot in the back and critically wounded, officials said Monday.

The boy, Zarriel Trotter, was struck by a stray bullet after two groups of youths began a “heated argument” Friday night on the city’s West Side and one person pulled out a handgun and started firing, Officer Jose Estrada said.

“He was not the intended target,” Officer Estrada said. “He was standing on the sidewalk.”

No one else was injured, and there have been no arrests so far, he added.

Zarriel, known to his friends and family as Zari, was one of several students who took part in a series of social media videos last year intended to highlight the toll that gun violence was taking on the black population.