A total of 650 law enforcement personnel served warrants on the residences of about 100 suspected gang members during the operation, authorities said.
"The damage we did was to the leadership of the gangs," said Pacheco.
"We were going after the top folks."
In addition to Riverside, suspects' homes in Beaumont, Mead Valley, Moreno Valley, Nuevo, Perris and Rubidoux were raided, according to the District Attorney's Office.
Pacheco said the sweep was the culmination of 14 months' work by the District Attorney's Office and the other agencies involved, with the goal of having "as large an impact as possible, in as many ways as possible."
The district attorney described the all-Hispanic Eastside Riva, numbering about 800, as Riverside's oldest and "most violent" street gang, at war with the 1200 Blocc Crips, an all-black gang numbering around 200, since the early 1990s.
Pacheco said the two sides have caused numerous casualties, including the deaths of innocent people, some of them children. Both gangs are into narcotics trafficking, he said. The Eastside Riva's drug trade is largely managed by the Mexican Mafia from prison, according to the U.S. Attorney's Office.