Updated 7.37pm: A boy's body has been found in the Waitarere Beach area where police have been searching for 10 year old Alex Fisher - and police have launched a homicide inquiry.

LISTEN Mayor Brendan Duffy speaks with Larry Williams

Earlier today: Huge police presence in search for Alex Fisher

Police say the body has not yet been formally identified, but it's likely to be that of Alex.

Area Commander Sarah Stewart said the body was found by helicopter around one pm - it's the worst possible outcome and they don't yet know the cause of death.

"The area where he has been found has been cordoned off, to allow a detailed forensic examination to take place."

"He will remain at the scene for the moment while the forensic examination continues."

Inspector Sarah Stewart personally delivered the news to Alex's family.

"This is devastating news to the family, and all of those involved in the search for him over the last three days."

"There is now considerable work ahead of us as we begin our homicide investigation" said Inspector Stewart.

"The investigation is likely to take some time as we build up the picture of the events that have led to this tragic outcome."

Local Mayor Brendan Duffy says it's the last outcome locals were hoping for.

"Absolutely gutted. Here we are in the middle of the school holidays and we've got a tragedy such as this in a small community. It's tough."

Police still want to hear from anyone who saw Alex, and his brother Eric, at Waitarere on Monday afternoon and evening.

The cause of death has yet to be established, but the circumstances are suspicious.