UPDATE - At least 15 die in knife attack outside Tokyo

TOKYO (AA) - Police are investigating a knife attack at a disabled facility west of Japan's capital Tokyo in which at least 15 people were killed and many others seriously injured.

Japanese news agency Kyodo reported that a knife-wielding man had attacked the Tsukui Yamayuri En facility in Sagamihara, Kanagawa Prefecture early Tuesday (late Monday GMT)

A man is reported to have turned himself in to a local police station around 3 a.m. (1800GMT Monday) where he was promptly arrested on suspicion of murder.

Firefighters have said that of those injured 20 are in a serious condition.

Reports say the man has admitted to the attack.