mplaint in San Francisco Superior Court seeking a civil injunction against the Down Below and Towerside gangs, which he said are believed to be responsible for at least 10 murders in the past three years, as well as other violence, drug dealing and nuisance behavior.
"The gang injunction we're pursuing today asserts the right of Visitacion Valley families to live in the peace and safety to which they're entitled," Herrera said in a statement.
If a judge approves the city's request at a yet-to-be-scheduled future hearing, the injunction would establish a 0.18-square-mile "safety zone" in which 41 named adult gang members would be banned from activities such as intimidation, graffiti vandalism, loitering, trespassing and other gang-related activities, according to the city attorney's office.
The proposed L-shaped zone would cover the Sunnydale, Heritage Homes and Britton Courts public housing developments and would be bordered by Schwerin Avenue, Visitacion Avenue, Hahn Street and the Sunnydale projects' northern, western and southern borders.
The zone encompasses both gangs' known turf areas, according to the city attorney's office.
According to Herrera, Down Below, based near the Sunnydale projects, and Towerside, which is based in the other two developments, have engaged in a "bloody rivalry" since 2007.
Murders, assaults, street robberies and shootings into inhabited homes and passing cars have become a pattern of daily life in the neighborhood, Herrera said. Other problems include drug dealing, vandalism, loitering, noise, car chases, and people being threatened for "snitching," he said.
District Attorney Kamala Harris, in the same statement, called gang injunctions "another vital tool in the prosecution of violent criminals."
The banned behavior -- all misdemeanor offenses if pursued criminally - carries a penalty of up to six months in county jail.
Herrera has been granted three other injunctions against five gangs in recent years: against the Oakdale Mob in Bayview-Hunters Point in 2006; the Norteno gang in the Mission District in 2007; and the Chopper City, Eddy Rock and Knock Out Posse gangs in the Western Addition in 2007.
Herrera cited arrest data showing a decrease in arrests of identified gang members after an injunction is issued, which he attributed to a decrease in criminal behavior.
"To date, no injunction has resulted in an observable migration of gang-related crime or nuisances to adjacent areas or to different neighborhoods," he said.