Twenty of the injured are in critical condition, the national fire department, which also performs emergency medical care, has said.
A 26-year-old man was arrested by police after the attack, national broadcaster NHK reported. He was said to be holding a knife.
Man who killed at least 19 at Japanese handicapped facility is a former employee in his 20s #Kanagawa #Tokyo pic.twitter.com/nYXnmN3kHZ
— Milo Stern (@Milo_Stern) July 25, 2016
Police are currently looking into the motive behind the attack, which happened in the city of Sagamihara, just west of Tokyo.
Images from the scene showed many ambulances near the Tsukui Yamayuri En (Tsukui Lily Garden) facility, which accommodates people with disabilities.
The attack took place at around 2:30 am local time on Tuesday. The knife-wielding man entered the facility from the outside and began attacking people, according to police.
Later, at around 3 am, a man reportedly turned himself in, saying: “I did it,” according to local media. A report by Daily-News.jp said that he was a former employee of the facility.
One resident told NHK that the man detained had blond hair and was wearing black clothes.
Can't be an act of a normal man, can't be an act of human either.Stabbing 19 disabled people to death means he is threat to mankind #Tokyo
— Zafar Abbas (@zafarabbaszaidi) July 25, 2016
Prayers now to Japan! How can a knife do this much damage held by one man? But it did….15 dead and 45 hurt. https://t.co/09zPwChbAe
— Lisa Renee Jones (@LisaReneeJones) July 25, 2016
Our prayers are with the people affected by the knife attack in Japan.
— AZ Intl Film Fest (@AZFilmFest) July 25, 2016
Worst mass murder in Japan since WW2+1995 Sarin. Our thoughts & prayers are with victims+families. #Sagamihara #Japan #Knife #Attack #Tokyo
— DK Matai♛ (@DKMatai) July 25, 2016