Terry Starks' voice rang out as he shouted through a bullhorn at a busy intersection in North Philadelphia.

"We're tired of the senseless violence out here," Starks, 34, called out to passersby and a handful of people milling in front of a bar at Ridge and Cecil B. Moore Avenues. "A brother lost his life out here Friday."

"We're Philadelphia CeaseFire," Brandon Jones, 26, yelled through another bullhorn. "We are here because we think change can happen here."

Their comments drew the attention of some pedestrians who paused to listen; others responded with wary gazes.

The pair, wearing orange T-shirts with the word Interrupter emblazoned on the back on a recent weekday evening, were participating with others in a "Walk for Peace" as part of an antiviolence outreach effort started in July in a hardscrabble slice of North Philadelphia.

The program's area of focus is the 22d Police District, which police said had 34 homicides in 2010. There have been 38 homicides in the district this year from Jan. 1 to Oct. 6, police said.

Philadelphia CeaseFire uses a public-health approach to reducing violence among teens and young men, said Marla Davis Bellamy, program director in Philadelphia.

The idea is to identify young people who have been shot and those at risk of being shot and to offer them guidance and counseling from street-smart "interrupters" who know violence firsthand.

CeaseFire approaches "the whole notion of violence being a public-health issue and looks at it as a disease," Davis Bellamy said during a recent morning meeting with the program's five-member staff, three of them ex-offenders, at its office at Temple University at Broad Street and Cecil B. Moore Avenue.

Philadelphia CeaseFire is based on CeaseFire Chicago, which was launched in 2000 and which was the subject of a documentary, The Interrupters. The effort uses a three-pronged approach to preventing violence: identification and detection; interruption, intervention, and risk reduction; and changing behavior and norms, officials said.

Gary Slutkin, an epidemiologist, developed the program in Chicago using techniques he employed during years of combating the spread of AIDS and other diseases in Africa. It was created in conjunction with the University of Illinois at Chicago School of Public Health. The Philadelphia program is linked to Temple University Hospital.

In a telephone interview, Slutkin discussed how the program looks at violence as an epidemic.

"There are two sciences that we are applying to this: the science of things that spread and how you prevent things from spreading more," Slutkin said. "The other science is the science of behavior."

Davis Bellamy said CeaseFire uses street-smart men and women, often ex-offenders, to mediate individual disputes, intercede in group disputes, and counsel young men at risk.

Slutkin said studies by the U.S. Department of Justice and several universities had documented significant reductions in homicides and gunshot cases in areas covered by CeaseFire.

"We get drops in shootings and killings in the range of 40 to 70 percent," Slutkin said. He said the Chicago program's success was being replicated in about 15 cities, including Baltimore. The program is also used in Iraq, Trinidad, and Kenya, he said.

Slutkin said CeaseFire, which works closely with police, is set up in areas with high concentrations of shootings. "We pick areas that have the highest amounts, and we will predetermine the area that we think we can cover with the amount of funding we have," Slutkin said.

Philadelphia CeaseFire is concentrated on a swath of the 22d Police District in North Philadelphia known as Police Service Area 2. The area runs west from 22d Street to the Schuylkill and north from Diamond Street to Lehigh Avenue, said Police Capt. Branville G. Bard Jr., the district's commanding officer. Bard said there had been about 15 shootings in the service area since July.

In addition to Davis Bellamy, former chief of staff for the Pennsylvania Department of Health, Philadelphia CeaseFire employs the three "interrupters" and an outreach coordinator. Davis Bellamy said the program was funded with a one-year $250,000 grant from the Pennsylvania Commission on Crime and Delinquency.

She said each interrupter receives about 60 hours of training from Chicago workers. Each works with about five or 10 "clients," young men from 15 to 28 years old, Davis Bellamy said.

During a recent morning staff meeting, Atiba Kwesi, 51, one of the interrupters, said connecting with young clients required patience and persistence. He said it took him more than a month just to get one client to tell him where he lived.

Kwesi, a tall, broad-shouldered man with thick braids who has spent more than 25 years in prison for robbery, theft, and other offenses, said: "When you ask kids why they do these things, they say: 'That's what we do.' They don't even think about why. It's very difficult to get them to stop."

To drum up community participation in a recent "Walk for Peace," three of the interrupters visited the Sharp Cuts Above barbershop at 26th Street and Cecil B. Moore Avenue on a recent afternoon.

Starks, one of the interrupters, who described himself as a former "stickup guy," urged shop owner Doug Walker to encourage his customers and others to attend the walk.

"This is real," Starks said of gun violence in the neighborhood. "This isn't affecting someone else's neighborhood."

He then pulled up his orange T-shirt to reveal a wide scar down his abdomen and said, "I'm a gunshot victim. I was unconscious for 19 days."

Walker replied that he often talks to teens in the community about the dangers of crime. "I've been in this neighborhood for 18 years. A lot of my kids got shot."

He said he supported antiviolence efforts. "We have to be a lighthouse for our young people," Walker said.

At the morning meeting at the CeaseFire office, Isaiah Turner, 19, a CeaseFire client, held his 7-month-old son, Namir. Turner, a 2010 graduate of Simon Gratz High School who described himself as a "former shooter" with an extensive juvenile record, said CeaseFire helped him change his view of violence and look for a job.

"I was one of those kids who was fighting other kids in school," Turner said. "I think this [violence] stuff gets handed down from generation to generation."

Amy Goldberg, director of trauma at Temple University Hospital, said the hospital refers young people who have been shot to Philadelphia CeaseFire.

"What's so great for us is that, unfortunately, we do see a number of patients who have suffered violent-crime injuries, whether that's gunshot wounds or stab wounds," Goldberg said. CeaseFire "gives us one additional resource to help them. That's wonderful," she said.

Bard, of the 22d Police District, said he welcomed Philadelphia CeaseFire workers to the district, though it was too early to tell whether their work was reducing shootings in the area.

CeaseFire is "making a difference just by the fact that they are touching some young men," Bard said.

"Some of these people are really bad guys. Now they are under the umbrella of CeaseFire," he said. "This gives me hope."