A 30-year-old man being questioned Thursday at a police box in Ichikawa, Chiba Prefecture, snatched an officer's handgun and shot himself in the head, police said.
The man, identified as an unemployed resident of Edogawa Ward, Tokyo, is in a coma, they said.
According to police, the man was being questioned by two officers -- a 24-year-old patrol officer and a 52-year-old lieutenant -- at the police box in front of JR Gyotoku Station after the manager of a local bar reported that he had been punched by the man.
The man approached the younger officer from behind just after the officer made a telephone call to the man's parents and scuffled with the lieutenant, who tried to stop him.
Police said he then grabbed the officer's gun from his waist holster and shot himself. The officers were unhurt.