A 12-year-old girl and a 17-year-old boy have died after a serious incident in the water off Bournemouth Pier.

Detectives have launched an investigation into their deaths following the incident, and a man in his 40s has been arrested on suspicion of manslaughter.

Dorset Police said it received a report at 4.32pm on Wednesday (May 31) from the ambulance service requesting assistance on the beach off Bournemouth Pier.

READ MORE: Two children die and man arrested after incident near pier 

Masses of emergency services personnel attended and ten people were recovered from the water, while the area was cordoned off.

A 17-year-old boy and a 12-year-old girl sustained critical injuries. Tragically, they both later died in hospital. Their families have been informed.

Bournemouth Echo: Air ambulances on Bournemouth beachAir ambulances on Bournemouth beach (Image: ProfDimitriosBuhalis)

The other eight people were treated by the ambulance service for injuries that are not life-threatening.

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.

Following enquiries a man aged in his 40s, who was on the water at the time, has been arrested on suspicion of manslaughter.

READ MORE: Leaders express sadness as two children die off beach

READ MORE: Man arrested after children die following Bournemouth beach incident

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.”

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.