Nineteen residents have been killed in a knife attack at a care centre for people with mental disabilities in the Japanese city of Sagamihara.
Such attacks are extremely rare in Japan – the incident is the worst mass killing in decades.
Police have arrested a man who worked at the centre until February, and who turned himself into police after the attack.
He reportedly said he wanted people with disabilities to “disappear”.
The brutal killings have shocked Japan, one of the safest countries in the world.
“The lives of many innocent people were taken away and I am greatly shocked. We will make every effort to discover the facts and prevent a reoccurrence,” Prime Minister Shinzo Abe said.
The suspect has been named as 26-year-old Satoshi Uematsu.
He sent letters to politicians in February in which he threatened to kill hundreds of disabled people during a night shift, Kyodo news agency reports.
“My goal is a world in which the severely disabled can be euthanised, with their guardians’ consent, if they are unable to live at home and be active in society,” Uematsu wrote in a letter to the speaker of the lower house of parliament, obtained by Kyodo.
He was kept in hospital for almost two weeks before being released.
“You could say there were warning signs, but it’s difficult to say if this could have been prevented,” Kanagawa prefecture governor Yuji Koroiwa said.
Uematsu drove to the Tsukui Yamayuri-en care facility, located about 50km (31 miles) from Tokyo, in the early hours of the morning, armed with several knives.
He entered one of the buildings by breaking a window at 02:10 local time (17:10 GMT), a prefectural health official said, and began attacking sleeping residents one by one in their rooms.
Staff called police around 20 minutes later to report what was happening.
The stabbing rampage lasted around 40 minutes across two buildings, the Associated Press news agency reports. Uematsu’s 19 victims were aged between 19 and 70, Kyodo said, citing the Sagamihara City fire department. -BBC