Nineteen people, including 13 primary school children, have been injured in a suspected stabbing by a man just outside of Tokyo.
Two children and an adult were without vital signs after the stabbing in Kawasaki city, southwest of central Tokyo, national broadcaster NHK said, citing police.
Japanese media will not usually specify that people have died until official confirmation from a medical professional.
The suspect was detained on the spot and was badly hurt after stabbing himself in the shoulder.
NHK said the man, likely in his 40s to 50s, reportedly began slashing at people waiting at a bus stop. Two knives, along with some victims, were found in a nearby park, it said.
Police say the 13 injured children are schoolgirls from Caritas Elementary School, and are believed to be between six and seven years old.
Violent crime is rare in Japan but there have periodically been high-profile incidents that have shocked the nation.
A stabbing spree on a school bus and a commuter bus in a Tokyo suburb in 2010 injured more than a dozen people.
Two years earlier, a 28-year-old man drove a truck into a crowded pedestrian crossing in Tokyo, killing three people, and then fatally stabbed four more.