Updated

Ashland County authorities warned residents Thursday not to pick up any hitchhikers as they continue to search for four suspects involved in a large-scale marijuana growing operation in the Chequamegon-Nicolet National Forest in northern Wisconsin.

Ashland County Sheriff Mick Brennan said nearly 10,000 marijuana plants were destroyed in the bust and had an estimated street value of $1 million. Brennan said it the biggest drug bust of its kind in the county.

"We still have law enforcement searching. Two suspects didn't even have shoes they left the camp so quickly. They're on foot in a vast forest area," the sheriff said. "It's uninhabited; there was no way to get into that area by vehicle. We had to come in on foot, and had to have it eradicated using helicopters."

One man was arrested Wednesday at the scene in a remote part of the 1.5-million-acre forest, 25 miles northwest of Park Falls. Authorities said they were alerted to the marijuana operation after a tip from a hunter in November.

The sprawling site had thousands of plants hidden over several acres and included a camp for the people cultivating the marijuana as well as loaded firearms when I was raided by about 175 law enforcement officials from 22 agencies.

"It feels good to get it out of there," Brennan said. "We wish would've gotten all five suspects. We're still working on that."