(AP)- Authorities have raided a huge marijuana-growing operation in the forest a mile and a half north of Strawberry.

Arizona Department of Public Safety Commander Dan Wells tells the Arizona Daily Sun that that it may be the biggest marijuana bust in U.S. history.

The pot-growing operation was discovered in the Fossil Springs Wilderness.

The operation involved U.S. Forest Service, Gila County S.O., DPS, DEA, and U.S. Fish and Wildlife. Four suspects are in federal custody, but the investigation and operation is on-going. A news conference is planned for Thursday morning.

Marijuana growing in national forests is becoming a growing issue. This year, there have been five marijuana gardens found in the Tonto National Forest and this one in the Coconino National Forest.

The Sun quoted law enforcement officials as saying it could take up to a week to eradicate the farm. The Flagstaff newspaper says the farm is located in a ravine in the wilderness area that lies at the southern end of the Coconino National Forest. A spokeswoman for the U.S. Attorney's Office in Phoenix declined comment.