SAN ANTONIO -- Pearsall police said they arrested 15 men and women during a warrant roundup in Frio County.

Officers said most of the suspects arrested are members of the Mexican Mafia.

Police said they found large quantities of heroin.

Pearsall Police Chief Joel Gonzales said the arrests took place because of Operation Red, a joint effort between a number of law enforcement agencies designed to pick up fugitives with felony warrants all over Frio County.

Gonzalez said the operation will continue.

"We're going to continue to do this kind of work until we can clear this county from any type of illegal activity we've been experiencing in the past," Gonzalez said.

Officials said they're looking for Rene Munoz, otherwise known as "Red."

Munoz is wanted in connection with a killing.

Investigators ask anyone with information that could lead to Munoz's arrest to contact them.