Three people, including two police officers, have been killed in Nagano in central Japan, and a suspect with a rifle and knife is holed up inside a building, according to police and media reports.

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 on Thursday in Nakano city in the prefecture of Nagano.

The three were taken to a nearby hospital, where the woman was later 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 near where the suspect was holed up, Kyodo News agency reported.

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

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

City officials urged those in the area to stay home.

No other details, including about the suspect and his motives, were immediately known.