Mr. Mensa, a Grammy-nominated artist who grew up on the city’s South Side, said he came up with the plan because he wanted to find a way to invest in the neighborhood. The timing of the sting operation — during a period of summer violence — was disrespectful, he said.

“To see the police escort a bait truck full of shoes through a low-income neighborhood where people can’t afford basic necessities, it seemed very representative of how ill-equipped they are to deal with the city’s issues,” Mr. Mensa said in an interview.

The “bait truck” was left near 59th Place and Princeton Avenue in Englewood, a neighborhood where nearly 60 percent of the residents earn less than $25,000, according to 2015 census data. It is also among the most crime-ridden, though last year it recorded fewer shootings and other violence than in past years.

The Chicago police referred questions to Norfolk Southern, which said the action was in response to cargo thefts that had included guns and ammunition. Earlier this month, the Chicago police superintendent, Eddie Johnson, said he would take a “hard look” at the episode, but defended the motives behind it.

“They had been experiencing a lot of theft of firearms over there, so we have a responsibility to keep these firearms off the street and out of the hands of the wrong people,” Superintendent Johnson told reporters.

Still, some critics have questioned why the Chicago police were involved at all, and encouraged the department to take responsibility, even if it only assisted with the arrests.

“If you plan on doing a murder and I come with you to drive the getaway car, I’ll go to prison too,” Mr. Mensa said. “Whether or not the initiative was an idea generated by the police, they’re an accomplice.”