A son of the chief of a city assembly in central Japan was taken into custody early Friday in connection with the deaths of four people, including two policemen, after holing up in his father's house for hours, police said.

An investigation source said the suspect is believed to be the eldest son of Masamichi Aoki, speaker of the city assembly in Nakano, Nagano Prefecture. He stayed inside the residence after allegedly stabbing a woman to death and fatally shooting two policemen with a hunting rifle nearby, the police said.

Police officers stand near the scene of a fatal stabbing and shooting incident in Nakano, Nagano Prefecture, central Japan, on May 25, 2023. (Kyodo)

The motive for the rampage and other details remain unknown.

The police also said an elderly woman was found injured and unconscious outside the house, and later pronounced dead. Local authorities had said earlier there was an injured man left unattended near the residence.

Two other women, including the suspect's mother, escaped the house and the 57-year-old assembly chief was confirmed safe.

The police initially received an emergency call at around 4:25 p.m. Thursday about a man stabbing a woman in the city, which lies to the northeast of the prefectural capital of Nagano.

An eyewitness working in a field at about 4 p.m. said he first spotted the attacker chasing a woman who was shouting for help.

The suspect, wearing camouflage clothing, a hat, sunglasses and a mask, then grabbed the woman by the arm before stabbing her in the back with a blade that appeared to be around 30 centimeters long. He stabbed her again in the chest while she lay facing upward, according to the eyewitness.

"I killed her because I wanted to," the suspect was quoted as saying when the eyewitness asked why he had done such a thing.

The woman was later pronounced dead and identified as Yukie Murakami, 66, who lived near the spot, according to the police.

As the man left on foot, the 72-year-old local rushed to his home about 150 meters away, called the police and took the officers to a parking area where the stabbing took place.

The attacker then reemerged as the police car was parking and immediately fired into the driver's side. The witness, terrified by the sound, ran away. He said he heard more gunshots but was too afraid to look back.

The suspect then entered the house of the assembly speaker, the police said.

Blaring police sirens disrupted the usually quiet area, dotted with homes and rice fields. Residents within a 300-meter radius of the crime scene were asked to evacuate.

The scene of the incident is about 2 kilometers west of Shinshunakano Station on the Nagano Electric Railway.

The two male police officers who died were identified as Yoshiki Tamai, a 46-year-old inspector, and Takuo Ikeuchi, a 61-year-old sergeant.

Kyodo graphics

A police officer controls traffic near the scene of a fatal stabbing and shooting incident in Nakano, Nagano Prefecture, central Japan, on May 25, 2023. (Kyodo)