It has been a bloody summer in cities across the country. Milwaukee surpassed its 2014 homicide total by mid-July. The nation's capital reached that milestone last week.

And in nearby Baltimore — where the spike in killing has combined with unrest over a national spate of deaths of unarmed black men at the hands of police — an especially daunting challenge has emerged, and produced two different responses.

Community leaders such as Ericka Alston are mobilizing on the ground, with grassroots efforts to instill lessons of nonviolence.

Across town, in a high-rise conference room downtown, Baltimore police are working on a very different message. Last month, the police department launched the war room, a physical and metaphorical effort to combat the spike in killings.