PRENTISS, Miss. (AP) — One arrest has been made and the search is on for other suspects in connection with the discovery of seven large marijuana fields covering about 40 acres in Mississippi’s Jefferson Davis County, authorities said Tuesday.

News outlets in Mississippi say federal, state and local authorities were processing evidence the day after the fields were discovered about 3 p.m. Monday.

Investigators believe the fields could be the work of cartels, based on the sophistication of the operation. The crop could be worth as much as $70 million.

“They had begun harvesting some of this for sale,” said Mississippi Bureau of Narcotics director John Dowdy. He said three search warrants had been issued. One person was in custody. “We have a number of other suspects we are trying to locate.”

Dowdy said the operation found Monday may be related to a pot field busted just over a year ago in Jefferson Davis County, which is about 60 miles southeast of Jackson. That time, around $20 million in pot plants were found and suspects had fled the area. Agents were able to confiscate the marijuana then, but no arrests were made.

Some of the plants found Monday are as high as 8 feet tall. Once again, there are irrigation systems and electricity that run throughout the fields, as well as areas to wash clothes and sleep. It’s unclear how many people may have been running the operation.