Updated

Federal agents have arrested 30 members and associates of a prison gang that worked with organized crime in Mexico to bring drugs into South Texas and distribute them north.

U.S. Drug Enforcement Administration Special Agent in Charge Javier Pena said Thursday that the sweep was the result of a four-year investigation by the DEA and FBI into the notorious Mexican Mafia prison gang.

The arrests were made Thursday morning in Laredo, with a couple addition ones in San Antonio and Austin. Officers with local police, sheriff's offices and the U.S. Immigration and Customs Enforcement assisted in the arrests.

Some of those arrested were already in custody, but most were on the street. They were expected to make their initial appearances in federal court Friday.