About a mile hike into the Rogue River State Game Area, hidden in the forest, somebody recently built a bunker, complete with a reinforced wall and sandbags, KTLA sister station WOOD reported.

“It is a mystery,” said the Kent County man who discovered the bunker on Friday and immediately tried reporting it to authorities.

He didn’t want to be identified, he said, in case it was created by a militia group, possibly as a private training grounds.

“It looks like it might be more of a militia, military-type of thing to me,” he said.

It’s not easy to find. The bunker is about 50 yards off a narrow trail, under a canopy of pines, maples and oaks and on a hill overlooking Spring Creek, which runs away from Spring Lake to the northeast. The trail starts on Red Pine Drive, north of 18 Mile Road NE, northeast of Kent City.

On Monday, the Kent County man almost couldn’t find it when he led Nexstar’s WOOD back into the woods. It’s so remote that cellphone GPS wasn’t working.

“It doesn’t belong here,” he said. “It’s state land and it’s an illegal structure here.”

It appears the bunker was built recently and might still be under construction, with a few freshly cut down trees lined up on the ground nearby. It’s about 15-by-15 feet and almost 3 feet deep.

“It looks like there’s a place to rest your elbow all the way around it for steadying your aim for shooting,” he said.

Sandbags stacked two high, about 70 in all, form an outer perimeter. About two dozen more sandbags are in a corner of the bunker.

“The sandbags, you don’t need them for paint ball. You don’t need them for a deer blind. It looks like they’re to stop incoming bullets. It’s on a hill. There ain’t going to be a flood here.”

Two of the walls are reinforced with intertwined branches. There’s a fire pit in the middle.

“It bothers me,” he said. “It looks like it was built for a purpose and it looks like a lot of effort went into it.”

He said he called the U.S. Department of Homeland Security, which referred him to the FBI, which referred him to local police. He said he then called the Michigan State Police, which sent him to the Kent County Sheriff’s Department, which referred him to the Michigan Department of Natural Resources.

Even if it were a deer blind, the DNR said it would be illegal because you’re not allowed to cut down trees or alter the land.

He was hoping police would set up trail cams to catch the culprit. Instead, he said, the DNR told him it planned to dismantle the bunker.

“I would think they would want to do some sort of investigation, try to figure out who did this and what their idea was behind it,” he said. “To not investigate it seems like a missed opportunity with everything going on nowadays.”