A young boy was left with a fractured skull after being physically thrown out of a nursery classroom on June 13, a Kyoto city official said Thursday.

A female employee threw the boy and two other 5-year-olds into the yard because they had been fooling around during gym class at the Kasuganoen nursery school in Kyoto, said Junko Ueda, an official with the city’s day care division. The nursery is privately run but has public accreditation.

It took the staff three hours to get the injured boy to the hospital.

The employee’s name is being withheld pending an investigation. She was identified as being in her mid-30s and responsible for janitorial and administrative work at the center; she was not a licensed child care worker.

The two other boys suffered no major injuries, another city official said.

The incident only came to light when the city office received an anonymous tip, despite a Health, Labor and Welfare Ministry rule mandating public nurseries to report any serious incident.

The nursery was issued a warning last year for having too few licensed personnel on its staff to watch over the children.

No one at Kasuganoen was available for comment.

“This sort of thing is inexcusable,” Ueda told The Japan Times. “The nursery completely lacks awareness. We intend to supervise it strictly.”

Ueda added that if the nursery fails to make sufficient improvements it could be stripped of its public accreditation.

On the morning of June 13, the three boys were fooling around in gym class, climbing in and on top of shelves, when the woman threw them outside, the city said.

No licensed teacher was present and there was a delay of three hours before the child was taken to the hospital. The investigation by the city officials found that the nursery initially told the boy’s parents he had simply fallen and hit his head.

The boy underwent surgery Monday and remains hospitalized. He is expected to be released in a couple of weeks.

“We haven’t heard of anything this serious in recent years,” Ueda said.

“Not only did the employee manhandle the boy, it took the nursery three hours to take him to the hospital. It also failed to report it. None of this should have happened, and it is a major problem.”

As of Thursday, the female employee had been suspended but not been fired.