Reacting to what he called a "disturbing level of violence" over the past several days that left 12 shot and four dead, Baltimore police Commissioner Michael Harrison pleaded for the public's help.

In at least three of the cases, Harrison said at a news conference, the victim was at least acquainted in some way with the person police believe shot them. And in many cases, police responded to the scene seconds or minutes after the sound of gunfire.

Harrison said he believes shooters are being protected by a "culture of violence" where even the people affected by gun violence fear reprisal if they speak out.

"Now officer are very often in the right places and right time, but violent crimes are being committed anyway, which speaks to a certain culture of violence where criminals do not fear any possible consequences from the criminal justice system," Harrison said. "So in our opinion, that culture of violence simply has to change."

This week, Harrison reassigned a dozen officers from specialized units to the Eastern District and used historical crime data to identify "micro-zones" where violent crime is likely to happen. He said the department will continue to evaluate that strategy's effectiveness.

Harrison said the zones are two blocks long and two blocks wide. Officers will be required to spend up to 20 minutes, three times per shift, doing enforcement and talking to people in the community. They are trying to put more officers in areas where historically much of the violent crime has occurred.

Engaging more in the community to help solve crimes result in a better pulse on the zones and being more proactive. Police do say the new strategy is similar to others tried in the past like hot spots. The difference is more community engagement and checks on businesses.

Baltimore has seen 152 homicides so far this year. Last week, Mayor Bernard C. "Jack" Young said he was "sick and tired" of hearing about violent crime in the city.

"I remain 100% positive," Harrison said. "I'm never going to be negative, because the people of Baltimore are counting on us to hope."

Harrison said that residents who call Metro Crime Stoppers at 866-7-LOCKUP may remain anonymous.

Michael T. Mancuso, the president of the city's police union, said in a statement that while the Fraternal Order of Police Lodge No. 3 "applauds" the effort, they feel that the targeting of "micro-zones" sounds similar policies that have been tried without success

"The BPD now has 500-600 less officers than when this strategy was last tried, and the math just doesn't add up," Mancuso said. "Less police officers and more zones to cover clearly means a thinly stretched patrol division."