“The number of injured people is now 19, including one who is seriously injured and now shows no vital signs,” Kawasaki Fire Department spokesman Keiichi Hayakawa said.
“A man stabbed them,” another spokesman for the department, Dai Nagase said.
“We received an emergency call at 7:44 am, which said four elementary schoolchildren were stabbed.” Public broadcaster NHK said at least three people were in critical condition.
Police said one suspect, a man, had been detained. NHK said he had stabbed himself, suffering a serious wound. The broadcaster said two knives were spotted at the scene, but there was no immediate confirmation from officials.
The attack occurred at a park not far from a local train station, local media said, at the time of the morning commute. Footage broadcast on local TV stations showed multiple police cars, ambulances and fire engines at the scene. Emergency medical tents were put up to treat the wounded.