A 4-year-old girl died Friday a day after she was found unconscious in a nursery school pool in the city of Saitama, the police said.
Miku Akanuma was found floating facedown Thursday afternoon. At the time, 19 children between 3 and 5 were playing in the pool, with two teachers supervising.
The girl was rushed to a hospital after a teacher called for help at about 3:40 p.m.
Saitama Prefectural Police investigators are treating her death as a case of professional negligence resulting in death, sources said. While the police suspect the girl drowned, an autopsy will be conducted.
Akiyo Mayuzumi, the school's 67-year-old principal, issued an apology after the incident.