CEDAR RAPIDS — Aaron Richardson, 15, and Robert Humbles, 14, were not alone when the shots that took Aaron’s life were fired, police said Friday.Police Chief Wayne Jerman disclosed the information as his department continued to investigate Aaron’s killing Sunday night in southeast Cedar Rapids, as well a separate killing Thursday night in northwest Cedar Rapids.At the same time, Mayor Ron Corbett said he is calling for a community summit to address the escalation of gunfire and violence that has been afflicting the city for months.Corbett said Friday that city residents have become “extremely uncomfortable” with the level of gun violence this year.