TOKYO - Japanese police on Friday detained a suspect who had holed up in a building after allegedly killing four people, including two police officers, in a gun and knife attack.
The man was taken into custody outside a farm near the city of Nakano in Nagano region, with police confirming a fourth fatality overnight -- an elderly woman who was found injured at the scene and later pronounced dead.
Another woman and two police officers were earlier confirmed dead in the attack.
Police told AFP that the 31-year-old suspect had been detained at about 4:30am and later confirmed he had been formally arrested on suspicion of murder using a suspected hunting rifle.
The rampage in a rural area of the western region was a rare instance of violent crime in Japan, which has a low murder rate and some of the world's toughest gun laws.
No motive has yet emerged in the killings, nor has the suspect been formally identified, though several local media reported he is the son of the speaker of Nakano's city assembly.
"We pray for the souls of the deceased and express our heartfelt condolences to the bereaved families," top government spokesman Hirokazu Matsuno told reporters.
"Police are investigating to uncover the whole picture of the incident, including how the crime developed and its background."
The attack started on Thursday afternoon, when a local man working on a farm saw a woman "running from the road saying, 'help me'," he told national broadcaster NHK.
"Behind her came a man wearing camouflage and carrying a large knife, who stabbed her in the back," the 72-year-old witness said.
He said he called emergency services while neighbours tried to resuscitate the woman.
The attacker announced: "I killed her because I wanted to," according to an eyewitness cited by Kyodo news.
Local media said he then fired what has been described as a hunting gun at police officers who arrived at the scene.
The officers were inside a patrol car and the attacker placed the weapon against a window of the vehicle and fired twice, NHK reported.
The slain officers were identified as Yoshiki Tamai and Takuo Ikeuchi.