Three female teachers who used to work at a nursery school in the central Japan city of Susono near Mt. Fuji were arrested Sunday on suspicion of repeatedly abusing toddlers in their care.

The teachers were held hours after police searched the private school following the city's disclosure Wednesday that they were involved in 15 cases of abuse between June and August, such as holding toddlers upside down by their feet and slapping their faces.

The three, who left the nursery recently, admitted the abusive behavior, also including forcibly removing their pants and brandishing a cutter knife in a threating manner, but said they were trying to discipline the children, according to the city in Shizuoka Prefecture.

Investigators enter a nursery school in the Shizuoka Prefecture city of Susono in central Japan to search the facility on Dec. 4, 2022. (Kyodo)

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The teachers were among six in charge of the 1-year-olds' class at the school, Sakura Hoikuen. The police, suspecting that the abuse at the nursery was continuous, will analyze seized documents.

The police searched the school apparently out of fear that the school may destroy evidence. They also searched the houses of the three suspects.

It is alleged that Toshihiko Sakurai, head of the school, had made its staff sign an oath not to tell others about the abuses.

Susono Mayor Harukaze Murata said Sunday he will file a criminal complaint against Sakurai on Monday for allegedly helping the suspects elude justice.

The police said the former teachers are Sachi Miura, 30, Kaori Komatsu, 38, and Rie Hattori, 39. They were arrested for their actions in June against three toddlers.

Miura is suspected of pushing a girl in the face on June 1, while Hattori allegedly hit a boy on the head on June 10. Komatsu is suspected of holding a boy upside down by his feet on June 27.

The city and prefectural governments on Saturday started carrying out a special audit of the school, questioning Sakurai and having him present the three teachers' work records, according to officials.

The abusive behavior was brought to light after the city received a report in mid-August. It had met with Sakurai for its probe but kept the case secret for more than three months.