At least 13 teenagers and children were shot in Detroit since June 27, when a 4-year-old and 18-year-old were shot to death at Skinner Playfield, and a 17-year-old injured — all because a teen suspect was mad that someone ripped off his ski mask on a bus that day,

"What we've seen in the past 30 days is our problems have changed and our strategies need to change," Duggan said.