PLYMOUTH (CBS) - For as long as there have been motorcycles, people have ridden dirt bikes in the Plymouth woods.

But on Thursday, on one of the trails under power lines, a rider discovered steel spikes in the middle of the trail, anchored to a piece of wood that had been buried.

"Very dangerous, very scary. We don't know of anyone getting hurt" said Plymouth Police Chief Mike Botieri.

And a few days ago, at a dirt bike trail in Myles Standish State Forest, a steel cable had been stretched across the trail.

"Cable is the most dangerous, that will decapitate you in a second," says Bobby Bettencourt, of Bettencourt Motorcycles in West Bridgewater. He said a rider going as slow as 25 miles per hour could be decapitated by a cable.

No one has been arrested in either case, but it has dirt-bike enthusiasts on edge.

"That's some serious stuff. You're talking about people's lives on the line," said Bettencourt