Tokyo, Dec 4 : Three female teachers, who previously worked at a nursery school in the central Japanese prefecture of Shizuoka, were arrested on Sunday for repeatedly abusing infants in their care, local media reported. The teachers were detained hours after police searched the private school called Sakura Hoikuen in Susono city, local reports said on Sunday. This came after the city's Wednesday disclosure that the teachers were involved in 15 cases of abuse between June and August, including holding one-year-olds in their care upside down by their feet, forcibly removing their pants, and threatening them with knives, among other abusive acts. The three, who were among the six teachers in charge of the one-year-olds' class but left the nursery school recently, admitted the abusive behaviour but claimed they were trying to discipline the children, according to the city in Shizuoka prefecture. According to local reports, the police will examine the records they have acquired as they believe the abuse at the nursery was continuous. The school had forced all of its workers to sign an oath not to divulge what happened there, so the search was believed to be conducted by the police out of concern that the evidence may be destroyed, Xinhua news agency reported. Toshihiko Sakurai, the school's head, was questioned and required to produce the work records of the three teachers as part of a special audit that the municipal and prefectural governments began on Saturday, said local officials. The school had previously been asked by local officials in mid-August to provide a detailed account of the abuse inflicted on each child, but the school, including its head, kept silent on the accusations for three months, informed sources said. One father said on Thursday he was totally shocked by the revelations of abuse at his daughter's school and that it was impossible to comprehend people carrying out such heinous acts. He added that he would not be able to sleep imagining that such abusive acts could have happened to his one-year-old daughter. /IANS