GREEN BAY, Wis. -- Authorities estimate they seized at least 50,000 marijuana plants during a sweep through a northeastern Wisconsin national forest.

Oconto County Sheriff Mike Jansen cautions the number is only an estimate. Wisconsin Attorney General J.B. Van Hollen says counting continues and the number currently stands around 10,000 plants.

More than 200 police, state and federal agents swept through the southeastern tip of the Wisconsin forest 50 miles northwest of Green Bay overnight Tuesday. The operation was the culmination of two months of surveillance on a group of Hispanic men investigators believe were the growers.

Eight men were charged in federal court on Wednesday. Four more were charged Thursday afternoon.