More than a dozen people are dead in a knife attack outside Tokyo, The Associated Press reported.
A knife-wielding man attacked a facility for the disabled and then turned himself in, police said.
Police were originally called to the scene 2:30 a.m. local time, USA Today reported.
According to AP, Japanese media reported between 15 and 19 people killed. Between 20 and 45 people were injured.
Japanese national broadcaster NHK said the suspect, 26, is a former employee at the facility, Tsukui Yamayuri-en, was arrested on suspicion of attempted murder, AP said.
Television footage showed a number of ambulances parked outside the facility, with medics and other rescue workers running in and out.