Lee’s Summit, Mo. ? Four men have been arrested in what is believed to be a multistate tractor-trailer theft ring after two of the suspects walked into a police station claiming they owned a truck that had been identified as stolen.

Investigators said in a news conference Wednesday that more charges are possible once they have determined the scope of the operation. So far, six stolen trucks and eight trailers have been seized, including two tractor-trailers stolen from a California Highway Patrol impound lot.