A four-year-old girl has died following an incident at a swimming pool at Waterworld, Staffordshire Police said.
The force was called to the water park in Hanley, Stoke-on-Trent, at around 4.20pm on Monday to reports of a girl in a critical condition.
She was treated at the scene and then taken to hospital for further treatment but she died there.
Her next of kin have been informed and are being supported by specially trained officers, police said.
Waterworld will remain closed on Tuesday "out of respect for the family", the water park said.
A witness told Stoke-on-TrentLive: "There was at least 8 police cars and around 4 ambulances when I went drove past the first time, all with their emergency lights on.
“Then I saw the air ambulance land on Autobrite Direct car park, with the paramedics running back towards Waterworld. I hope everyone’s okay. It looks very serious from there being so many police and ambulances present at the scene."
Another witness told the outlet: "I'm not sure what's happened, but it seems major!"
The Waterworld statement continued: "It is with great sadness that we learned of this little girl's passing this evening.
"All our thoughts are with her family and loved ones during these extremely difficult times.
"Waterworld is in shock and has decided to remain closed tomorrow out of respect for the family."
They added that the park is working with the authorities.
Detective Chief Inspector Lucy Maskew said: "Our thoughts are with the family at this terribly sad time.
"We are now making inquiries and looking to establish the circumstances of the incident.
"We would ask that members of the public avoid speculating in these early stages of the investigation and allow the family to grieve."
Anyone with information is asked to call 101 quoting incident number 460 of August 4.
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