An 8-year-old girl was confirmed dead at a Tokyo hospital Thursday after being found underneath an inflatable island in a swimming pool at Toshimaen amusement park.

According to the Metropolitan Police Department, Yuka Morimoto of Asaka, Saitama Prefecture, likely drowned after getting trapped under the floating island. The pool is 1.2 to 1.9 meters deep, and the girl was said to have been wearing a life jacket.

The police said seven lifeguards were keeping watch over the pool.

The girl came to the park with her parents and younger sister. Her body was discovered 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 drowning took place, an area that requires an additional entrance fee, until it can be determined what happened.