PITTSBURGH — The police chief called on the city’s black community to “step up” up in the wake of seven fatal shootings this month, including five since Sunday, blaming most on drug trafficking, gangs and other criminal activity.

The killings occurred between Aug. 4 and Sunday and the victims — all black males — ranged in age from 3 to 29. All but one remains unsolved and all have one other thing in common: witnesses who are unwilling to cooperate with police, out of fear, distrust or some other concern.

“If you have 40 people standing around (after a shooting) and they’re all talking about it, they have to include us in that conversation,” said Police Chief Nate Harper, who is black. Even if all people have is rumors, police would rather spend time checking them out than be out of the loop, he said.

Three of the shootings, in particular, illustrate the various facets that make them so worrisome to police: an innocent toddler is shot inside a home; a 14-year-old boy mixed up in wrongdoing is killed; and a 19-year-old is gunned down in what police believe may be the same gang-related vendetta that claimed the life of his innocent 12-year-old sister more than three years ago.

A fugitive task force arrested 18-year Gregory Dalton more than 40 miles away in Indiana County Thursday in the Aug. 9 shooting of 3-year-old Zy’Miere Sewell. Police initially believed the child might have shot himself while watching TV at about 1 a.m.