The effort, which starts today, targets a district that "has been troubled by gun violence," Street said, and is viewed as one of the most dangerous areas in the city.
"We are starting an enhanced program of public safety," Street said. "We will be very aggressive in deploying in this area."
As of Tuesday, there had been 79 murders in the city this year, a 27 percent increase over a year earlier. Philadelphia's total exceeded those in much bigger cities; for instance, New York, with eight million people, had 66 homicides as of Sunday.
The deployment in the Southwest is similar to Operation Safe Streets, with the goal of saturating the area with a heavy police presence.
The deployed officers come from the department's elite Strategic Intervention Tactical Enforcement unit, the Highway Patrol, the Narcotics Strike Force, and other assignments in the 12th District.
Street and Johnson emphasized that the deployment would not take officers from other police districts.
Street said the deployment would involve a "holistic approach," adding that other city departments would work in Southwest Philadelphia to clean and seal vacant properties and lots, remove trash and graffiti, and "provide an enhanced level of social services to the community."
"We expect to have an unprecedented partnership with the people in this community," he said.
Johnson said: "We're doing everything we can to improve the quality of life. . . . We're out here to support the community."
The initiative targets Southwest Philadelphia, he said, because "you put a tourniquet where the bleeding is. This is where the bleeding has been."
Johnson also issued a warning to those on probation or parole in the area.
"Everyone in this district who violates probation or parole, we're coming after you," Johnson said.
Officials said the initiative would include the Departments of Licenses and Inspections, Streets, Water and Recreation and the Fire Department.
During the roll call, the 80 officers presented their guns for inspection, which is standard for roll calls at Philadelphia police districts.
What made yesterday's unusual was that it was held in a busy public place in view of residents.
Street said enforcing youth curfews would also be a part of the initiative.
"If we keep children off the streets at night . . . this will be a stronger community and a safer community," he said.
Contact staff writer Vernon Clark at 215-854-5717 or firstname.lastname@example.org.
Inquirer staff writer Michael Matza contributed to this article.