A 15-year-old girl has died after being pulled from the sea at Cleethorpes beach, police said.
She was one of two teenagers airlifted to hospital just after 7.30pm on Saturday after a major search by coastguards, the fire service and police for the missing pair.
The other child, a boy, has been discharged from hospital, Humberside Police said.
The force said in a statement: “We can confirm that a girl, aged 15, has sadly passed away following a multi-agency search to locate two missing children off the coast of Cleethorpes, North East Lincolnshire.”
It added that the alarm was raised at around 2pm on Saturday.
“At that time it was unknown if they had entered the water. Following a multi-agency response, two children were recovered from the water.
“Both needed immediate urgent medical care,” the police said.
“Sadly, the girl, who will not be named at the request of the family, did not recover.”
Detective Inspector Nathan Reuben said agencies were working to piece together how the tragic accident came about.
Cleethorpes beach is a popular local spot and temperatures hit 27C on Saturday.
Mr Reuben said: “Our thoughts and sincere condolences are with the family at this incredibly difficult time.
“We ask that they are given the time and space to process this tragic news.
“The family is being supported by specially trained officers.
“The boy who was also recovered from the water was taken to the hospital to receive medical care.
“He has since been discharged.
“We are working together with all the relevant agencies including Humberside Fire and Rescue services and the Coastguard to fully understand the circumstances of the tragic accident.”
