A masked man carrying a rifle and a knife was holed up in a building Thursday in Nagano in central Japan after four people were injured, one of whom later died, police said.
The injured included two police officers but it was not immediately known if their injuries were gun wounds, police said.
Officers had rushed to the scene after a pedestrian reported a commotion in Nakano city in the central Japanese prefecture of Nagano.
A witness told NHK public television that a woman fell while being chased by the suspect, who then stabbed her with a knife and shot at two police officers as they arrived at the scene.
The police officers were unconscious, and a fourth person who was injured could not be rescued because he was near where the suspect was holed up.
The three were taken to a nearby hospital, where the woman was later pronounced dead, police said.
Police described the suspect as a man wearing a camouflage outfit, a hat, a mask and sunglasses, Kyodo News agency said. City officials have urged those in the area to stay home.
No other details, including about the suspect and his motives, were immediately known.