Authorities charged leaders of a California prison gang Wednesday with orchestrating killings, drug sales and other crimes from behind bars in a case filed two weeks after a different prison gang was accused of organizing drug trafficking and killings from their state prison cells.

More than 50 people were arrested in the latest case on suspicion of having connections to the Nuestra Familia prison gang and affiliated Norteno street gang, said U.S. Attorney McGregor Scott and California Attorney General Xavier Becerra.

The alleged crimes include murder, robbery, extortion and trafficking in drugs and illegal firearms in Kings and Tulare counties, about 200 miles southeast of Sacramento.

Federal authorities say high-ranking Nuestra Familia members Salvador Castro Jr., 49, and Raymond Lopez, 31, used contraband cellphones inside Pleasant Valley State Prison in Fresno County to have narcotics shipped from Mexico for distribution by other gang members.

Castro has been serving a life sentence since 1997 for a third-strike conviction for possession of a firearm by an ex-felon. Lopez has been serving a 21-year term since 2013 for assault with a semi-automatic firearm with a street gang enhancement.

Neither had defense attorneys listed in court records to comment on the new allegations.

"The fear and violence that criminal street gangs are perpetrating in our communities cannot be tolerated," Becerra added in a statement.

Work is being done by the California Department of Corrections and Rehabilitation to "try to mitigate the negative impact these gangs can have in the rehabilitation efforts of inmates serving their time, as well as in prison operations and in our communities," department spokeswoman Vicky Waters said in a statement.

The multi-agency investigation began in September after a spike in unsolved killings since 2015 in the Central Valley cities of Hanford, Kettleman City and Avenal.

A sweep this week resulted in the seizure of 53 firearms and more than 36 pounds of drugs, authorities said.

U.S. prosecutors charged 19 other Central Valley residents with assorted crimes that could carry life sentences. They include eight alleged gang associates charged with distributing large amounts of methamphetamine and other drugs.

The crackdown came two weeks after U.S. prosecutors charged alleged leaders and associates of the Aryan Brotherhood prison gang with directing killings and drug smuggling from within California's most secure prisons. Those charges involve five slayings and accuse an attorney of helping smuggle drugs and cellphones to aid the gang.

An affidavit by FBI Special Agent Ryan Steger says authorities began tapping smuggled cellphones to implicate Lopez and Castro, who uses the nicknames "The Old Man" and "Gangster."

Intercepted conversations "provided insights into the critical workings of the NF, and their conversations also revealed an ongoing drug trafficking conspiracy," according to the affidavit.

It's the latest attempt to disrupt the gang founded to challenge the Mexican Mafia.