Investigation launched and a man arrested.
A 12-year-old girl and a 17-year-old boy have died following an incident in the water just off Bournemouth beach.
They were rescued from the water on Wednesday afternoon but sadly died later in hospital.
Eight other people were also rescued from the water and were treated by the ambulance service for injuries that are not life-threatening.
Following enquiries, a man aged in his 40s who was on the water at the time has been arrested on suspicion of manslaughter.
An investigation into the circumstances surrounding the incident has been launched with Dorset Police working alongside the Marine Accident Investigation Branch and the Maritime and Coastguard Agency in accordance with established protocols.
Detective Chief Superintendent Neil Corrigan, of Dorset Police, said: “Our thoughts are with the loved ones of the young people who tragically died and we are doing all we can to support their families.
“I understand the beach was very busy at the time of the incident and I would ask anyone with information that may assist our enquiries to please come forward.
“We are at the early stages of our investigation and would ask people not to speculate about the circumstances surrounding the incident.”
BCP Council Leader, Cllr Vikki Slade added: “We are heartbroken to hear the news that two young people rescued at Bournemouth Beach earlier today have died, and our thoughts are with their family and all those involved in the rescue.”
Anyone with information is asked to contact Dorset Police at www.dorset.police.uk or by calling 101, quoting occurrence number 55230083818. Alternatively, independent charity Crimestoppers can be contacted anonymously online at Crimestoppers-uk.org or by calling Freephone 0800 555 111.