More than 20 people appeared before a federal court judge following Tuesday's raid on dozens of homes as part of a federal crackdown on indoor marijuana growing operations.

The more than year-long investigation was dubbed operation "Green House Effect" and involved suspected members of a Vietnamese crime ring.

According to the U.S. Attorney's Office, 24 people have been arrested and a total of 19,000 marijuana plants were seized during the operation.

Drug Enforcement Administration agents conducted search warrants on 60 properties in Harris, Fort Bend and Montgomery counties and reported 40 of those locations were active hydroponic marijuana "grow houses." DEA officials said each active location had anywhere from 100 to 850 marijuana plants in varying stages of growth.