A couple and their teenage daughter have died after getting into difficulty in the sea off the West Sussex coast, police said on Tuesday.

A man, a woman and a teenage girl died after the incident in Shoreham-by-Sea, the chief superintendent of Sussex police, James Collis, said.

A younger girl from the same family was taken to hospital in a critical condition, Collis added. The next of kin have been informed.

Collis said it is understood that all four got into difficulty in the water after going for a swim.

He added: "Our thoughts are with the friends and family. I know this incident will have a profound effect on the community."

Emergency services were called at about 2.40pm to reports of four people in difficulty in the sea. All four were brought to shore. The coastguard is not searching for anyone else.

A spokesperson for Air Ambulance Charity Kent Surrey Sussex said both of its helicopters and critical care team had been sent to the scene as part of the response, and Shoreham RNLI said its lifeboat had been called out at 3pm.

Tom Rutland, the MP for Shoreham, offered his condolences. "My thoughts are with the family and friends of those who have lost their lives, and I know the whole community here in Shoreham will be hoping and praying for the recovery of the young girl receiving medical treatment in hospital," he said.

A local said the water was "incredibly rough" and the winds were "incredibly strong", Sky News reported.

Rutland thanked the emergency services, which he said "responded swiftly" and "worked tirelessly in exceptionally difficult circumstances".

Speaking at a press conference, Collis added: "At this point we believe all four entered the water from the land to swim and sadly got into difficulty. Our partners in His Majesty's Coastguard have completed an extensive search of the water and we are not searching for anyone else.

"I would like to thank the public for their patience and understanding during the emergency response.

The A259 Brighton Road was blocked in both directions from New Road to Kingston Lane because of the incident.

There have been a number of water-related deaths in recent months during the extreme heat.

On Saturday, a 12-year-old boy drowned in the River Lea, near the Hackney Marshes, in north-east London.

In April, a woman and her young child died after getting into difficulty in the water in west London. Both died at the scene in Elthorne Park, Ealing, the Metropolitan police said.

Anyone with information or with video footage relating to the incident in Shoreham-by-Sea should contact Sussex police.