Three people have been killed and one injured in a shooting and stabbing in Japan, with the suspect having barricaded himself inside a building, according to local media reports.

A woman fell while being chased by a masked man, who then stabbed her with a knife and shot at two police officers arriving at the scene with a rifle in Nakano city in the prefecture of Nagano, a witness told public broadcaster NHK.

The three were taken to a nearby hospital, where the woman was pronounced dead, police said.

The two police officers also died later, according to NHK.

A fourth person who was injured could not be rescued because he was lying near the scene of the attack, Kyodo News agency reported.

The suspect is believed to have barricaded himself in the house of the city council president and several gunshots were heard nearby the site, the news agency added.

NHK footage showed uniformed police wearing bulletproof vests and carrying shields with an ambulance nearby.

City officials urged those in the area to stay at home.

Police described the suspect as a man wearing a camouflage outfit, a hat and mask and sunglasses, the Kyodo News agency said.

No other details about the suspect and his motive are known.

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Crimes involving guns are rare in Japan, where gun ownership is tightly regulated and anyone seeking to own a gun must go through a rigorous process to get a licence.