NORWALK, Wis. -

A man who fell from the roof of a moving vehicle in a Monroe County field has suffered critical head injuries.

Sheriff's deputies say 22-year-old Joseph Miller climbed through the sun roof and was riding on top of the vehicle shortly after midnight Friday in a field on private property near Norwalk. He fell off the vehicle when the driver put it in reverse and struck his head on a rock.

The driver took Miller to Franciscan Skemp in Sparta. Miller transferred to Gundersen Lutheran Hospital in La Crosse with life threatening injuries. Sheriff's officials say he's currently in critical condition.