UNION CITY, Tenn. (AP) -- Authorities are increasing their estimate of the number of marijuana plants found in a massive outdoor growing operation in Obion County.

Law enforcement found the plants on Monday and initially said there were at least 50,000 mature marijuana plants growing over the 10-acre site in a heavily wooded hillside west of Hornbeak.

But as they started removing the plants on Wednesday, they seized an estimated 362,000 marijuana plants with a street value of about $434 million, the Union City Daily Messenger reported.

Obion County Sheriff Jerry Vastbinder called it a very sophisticated operation that included barracks, underground tunnels, showers, generators, a kitchen, an irrigation system and lights.

No arrests have been made, but investigators are gathering evidence at the scene, said Chief Deputy Kent Treece.

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