The city’s fire department said it received an emergency call at 7:44 a.m. Tokyo time that a number of people had been stabbed, department spokesperson Akira Tanaka told CNN.
Three people, including an elementary school student, are in critical condition, according to Japanese public broadcaster NHK.
Eight children and seven adults received treatment, according to NHK.
NHK reported that a suspect had been detained. He is in his 40s or 50s and has a serious injury.
Kawasaki is about 13 miles (21 kilometers) from Tokyo.