A 25-year-old man is seriously ill in hospital after being found unconscious in a road in Kent.
Kent Police said the man was found at about 0430 BST in West Hill, Dartford, with no sign of visible injuries.
The man's condition was described by doctors as life-threatening, a police spokesman said.
Officers are examining CCTV footage and an investigation is under way in the area. Anyone with information has been asked to contact the force.