An eight-year-old girl drowned in a swimming pool and was confirmed dead at a Tokyo hospital on Thursday after she was found underneath an inflatable island.

Yuka Morimoto from the city of Asaka in Saitama Prefecture, north of Tokyo, was found in the 1.2-1.9-meter-deep pool which features a floating island inside Toshimaen amusement park, said the Metropolitan Police Department, pointing to the possibility she may have become trapped somehow.

[Photo courtesy of Toshimaen]

The police said seven lifeguards were keeping watch over the poolside at all times and the girl was said to have been wearing a life jacket. She came with her parents and younger sister, and was found during a regular inspection at 2 p.m., two hours after the last inspection, the police added.

The operator of Toshimaen closed all swimming pools Friday and said it will not reopen the section that includes the pool where the incident happened, an area that requires an extra entrance fee, until it can be determined what happened.