Authorities in Japan announced on Friday that a 31-year-old man was detained in a remote region for suspected murder after four people were murdered in an unusual shooting and stabbing event that involved a 12-hour standoff with police.

According to the chief of the Nagano prefectural police, the suspect had holed himself in his residence after shooting two police officers who came on the scene in response to a report of a lady being stabbed. He stated he shot with what seemed to be a hunting rifle.

The suspect is the son of the head of the Nakano city council, public broadcaster NHK reported.

The two police officers and the woman were taken to hospital and pronounced dead within hours, the police chief, Iwao Koyama, said.

“This is a heinous crime that has aroused great fear in the residents of the prefecture and society at large,” he said.

Another elderly woman also died after an apparent knife attack, police said. She had been lying on the ground outside the house since Thursday afternoon and police had been unable to get to her, media reported.

Police detained the man around 4:30 a.m. (1930 GMT) on Friday, about 12 hours after the first call to emergency responders, media said. He was arrested for the suspected murder of one of the police officers, Koyama said.

Shootings are extremely rare in Japan, where gun ownership is tightly regulated and anyone seeking to own a gun must go through a rigorous vetting process. The suspect had a licence for a hunting rifle, the head of the National Public Safety Commission told a separate briefing.

The suspect’s mother and aunt who were in the house with him escaped on their own, Koyama said.

Few other details were known, including the suspect’s motive.