Police arrested the man , 26, after he turned himself in at a police station in the city of Sagamihara west of Tokyo, shortly after 03:00, NHK channel said . State radio said police said they received a call from an employee at the facility , saying a man with a knife broke into the building. Police said the suspect told them he was a former employee at the center , according to the radio . The TV footage showed several ambulances parked outside the facility, with nurses and other rescue workers working inside and outside , and , according to The Associated Press . Kyodo News Agency said 28 people were wounded .