The three-year-old boy who was flown to hospital last night following an incident in Upavon has died.
Wiltshire Police were called shortly after 7pm yesterday to reports of a missing child.
A spokesman said today: "Sadly, the child was found shortly after 7.20pm in a nearby swimming pool.
"He received emergency medical treatment at the scene but was unresponsive.
"He was airlifted to Southampton General Hospital where he tragically passed away in the early hours of this morning."
Formal identification has yet to take place.
Wiltshire Police will now work with Hampshire Constabulary and partner agencies to prepare a report for the coroner's office.