SAGAMIHARA, Japan (REUTERS) - Shock and bewilderment gripped neighbours of a disabled centre in a town near Tokyo on Tuesday (July 26) after a man stabbed and killed 19 residents in their sleep and wounded dozens more in Japan's worst mass killing in decades. "This kind of thing doesn't happen in Japan. It's unthinkable it happened so close to me," said retiree Masae Mizoguchi,78, who lives up the hill from the Tsukui Yamayuri En (Tsukui Lily Garden) facility.

Residents of the town of Sagamihara in Kanagawa Prefecture, about 40km south-west of Tokyo, woke in horror on Tuesday to learn that a man had broken into the disabled facility overnight and stabbed residents as they slept.

"These people were severely disabled, and they were asleep. That's why he was able to kill so many," the retiree said.

Japan has largely been spared the mass killings that have become all too common elsewhere in the world, partly due to its strict gun-control laws.

"This is a peaceful, quiet town, so I never thought such an incident would happen here," said another neighbour Oshikazu Shimo, one of many Sagamihara residents who gathered nearby as the buzz of cicadas was heard in the humid summer air.

Police have arrested Satoshi Uematsu, 26, a former employee at the facility. A Sagamihara city official said Uematsu had been involuntarily committed to hospital on Feb 19 for fear that he would harm others.

He had come to authorities' attention after saying he was willing to kill severely disabled people, but was discharged on March 2 after a doctor deemed his condition had improved, the official said.

Police said they were still investigating the suspect's motive, but Chief Cabinet Secretary Yoshihide Suga said there was no information linking Uematsu to Islamist extremists.

Japan's worst previous mass killing was in 2008, when a man drove a truck into a crowd and began stabbing people in Tokyo's popular electronics and "anime" district of Akihabara, killing seven people. In 2001, a knife-wielding man killed eight students in an elementary school in Ikeda in Osaka Prefecture.

The Sagamihara facility is located in a valley nestled between mountains, at the end of a street of modest houses interspersed with persimmon orchards and vegetable gardens.

In a nearby amusement park, the Ferris wheel and other rides were operating normally. "That kind of person can't defend themselves. That's why so many died," taxi driver Susumu Fujimura said of the victims.

"It makes you weep to think of somebody just murdering them. He said 'we should get rid of disabled people' but he's the worthless one," he said.