SAN DIEGO — Five men pleaded not guilty Wednesday to charges of kidnapping and torture in what prosecutors said was a sophisticated kidnap-for-ransom ring.

The five were involved in the kidnapping of Eduardo Gonzalez Tostado, 32, whose family paid $200,000 in ransom, said San Diego Deputy District Attorney Mark Amador.

“The defendants are members of a sophisticated murder crew that has been operating in San Diego for the past couple of years,” Amador told Superior Court Judge David Szumowski.

Tijuana, Mexico, across the border from San Diego, has witnessed a spate of kidnappings in recent years, often linked to drug violence. Kidnappings are extremely rare on the U.S. side of the border.

Gonzalez, a Mexican citizen with legal residence in the U.S., was kidnapped June 8 in San Diego County and subdued with a Taser stun gun, Amador said. He was rescued Saturday in an FBI raid on a home in Chula Vista, a suburb of 230,000 people about eight miles north of the U.S.-Mexico border.

Investigators found assault weapons, handguns, chains and handcuffs that were used to subdue Gonzalez and possibly other kidnapping victims, Amador said.

The prosecutor declined to elaborate on alleged victims or the kidnapping ring.

The suspects — Ruben Flores, Juan Gonzalez Estrada, Raul Gamez Rojas, Carlos Pena and Jose Oliveras — each face one count of kidnap for ransom and reward, with a special circumstance of holding their victims in a manner likely to cause great bodily harm or likelihood of death.

Flores also pleaded not guilty to a single count of possessing firearms. His attorney, Jan Ronis, declined comment after the court hearing, but said his client’s real name is Jorge Rojas Lopez.

Szumowski ordered them held without bail.

All face the possibility of life in prison without the possibility of parole, Amador said in court.

None of the five men are U.S. citizens, Amador said. He did not know their immigration status or nationality.

A public defender representing several of the men declined comment after the hearing.