Police in central Japan have arrested a 31-year-old man in connection with the killing of four people, including two police officers, in a shooting and stabbing attack.
Police have identified the suspect as Aoki Masanori, the son of Nakano City assembly speaker Aoki Masamichi.
Police say Aoki has confessed to killing one of the officers, saying, "It's true that I shot him. I killed him."
Investigative sources say Aoki told police he carried out the knife attack because he thought he was being spoken ill of, and he shot the officers because he thought they might shoot him.
After the killings, Aoki barricaded himself in the house where he lives with his parents and an aunt. Police say he was armed with a rifle and the standoff lasted for about 12 hours. When he emerged from the house at around 4:30 a.m. on Friday, they detained him.
Police received a report at around 4:30 p.m. on Thursday saying a man had stabbed a woman. When officers arrived at the scene, the man opened fire on them with what appeared to be a hunting rifle. The woman and two police officers died. Another woman found later lying on the ground at the scene was confirmed dead.
The suspect fled on foot and holed himself up in his father's house.
Nagano Prefectural Police chief Koyama Iwao has given a news conference in which he called it an "extremely vicious crime." He said the suspect has confessed, but gave no further details.
A police official at the news conference said officers assumed they were responding to a knife attack, but it turned so quickly into a shooting that they had no time to prepare, and the officers were not wearing bulletproof vests when they were shot.
Koyama says the suspect's mother and aunt managed to escape from the house.
Police officials say the suspect did not make any requests to the police while he was barricaded in the house. They say they persuaded him to surrender with his hands up.
One neighbor says the murdered women were good friends, and often strolled around together.
The suspect's father has resigned from the city assembly.
The police say the suspect received a permit to keep a shotgun in 2015, and for other types of guns later. He currently has permits to possess four firearms.
Gun ownership numbers are low in Japan and gun crime is rare. Last year, there were just nine gun-related incidents reported nationwide. The incidents resulted in four deaths.