Three members of the same family died on Tuesday after getting into difficulty in the water at Shoreham, Sussex
A fourth family member is in a critical condition in hospital, with police yet to give an update on the girl's condition
A man, a woman and a teenage girl died after being pulled from the sea, Sussex Police said - flowers have been left at the scene this morning
"At this point we believe all four entered the water from the land for a swim and sadly got into difficulty," Chief Superintendent James Collis said last night
Collis said police were called at around 14:40 BST to the incident near Shoreham port
The incident, described by BBC reporter Callum French as "the biggest turnout [of emergency services] I have seen", took place at Kingston Beach, a short distance from Shoreham Port.
Shoreham-by-Sea is about a 6.3 mile (10.1km) drive away from Brighton.
George Carden
in Shoreham
There is a real sombre mood down here at Kingston Beach, in Shoreham-by-Sea, on a rainy morning, where two bouquets of flowers have been laid near the RNLI lifeboat station in memory of the three people who have died.
No emergency services are here this morning and the A259 has been reopened after its closure last night.
A number of TV crews are also at the scene.
Floral tributes have been laid in memory of the three people who have died after getting into difficulty in the water off the coast of Shoreham-by-Sea.
Reporters from the BBC will be speaking to the local community this morning as it tries to come to terms with the tragedy.
Image source, Eddie Mitchell
Image source, Eddie MitchellWe learned yesterday that three members of the same family had died after getting into difficulty in the water off the coast of Shoreham-by-Sea, West Sussex.
Sussex Police said a man, woman and teenage girl had died, while a younger girl from the same family was in hospital in a critical condition.
Emergency services were called at about 15:00 BST on Tuesday, with the coastguard, police, several ambulances and an air ambulance rushing to the scene.
A BBC reporter in Shoreham says that locals have been greatly affected by the tragic incident.
Image source, Eddie MitchellThree members of the same family - a man, woman and teenage girl - have died after getting into difficulty in the sea in the town of Shoreham, near Brighton.
Another girl - also from the same family - is in a critical condition after being pulled out of the sea and is being treated in hospital.
Police say emergency services were called this afternoon to support four people in difficulty in the sea. Coastguard crews, police, several ambulances and an air ambulance rushed to the scene. The three died despite the best efforts of paramedics, police said.
The next of kin have been informed.
The BBC's reporter in Shoreham Sam Harrison says local have been hit hard - there is a great level of shock in the town.
Local MP Tom Rutland says he is deeply saddened by the tragedy.
"I know the whole community here in Shoreham will be hoping and praying for the recovery of the young girl receiving medical treatment," he says.
We're pausing our coverage, read our report here.
Tom Rutland, the MP for Shoreham, says he is "deeply saddened" by this evening's "tragic news".
"My thoughts are with the family and friends of those who have lost their lives," he says in a statement shared on Facebook.
"I know the whole community here in Shoreham will be hoping and praying for the recovery of the young girl receiving medical treatment."
Sam Harrison
Reporting from Shoreham
It has been a tragic evening here in Shoreham.
It was a truly chaotic scene earlier today. Emergency services were called here as four people got into difficulty in the water.
There was an enormous emergency response and people were wondering what had happened.
We now know a man, woman and teenage girl have tragically lost their lives. They have all been confirmed from the same family.
A younger girl has been taken to hospital in critical condition.
This has caused a great level of shock. It will hit locals very hard.
People were taken aback by the scale of the operation, and people knew immediately that something very serious had happened. There was a huge wave of ambulances in the road stretching behind me.
Collis says all four people entered the water from land for a swim and got into difficulty.
The coastguard is not searching for anyone else.
He thanks the public for their patience and asks anyone with information or video footage to contact the police online.
A younger girl has been taken to hospital and she is in critical condition, Collis says.
He adds that all four people who got into trouble were from the same family.
Chief Superintendent James Collis from Sussex Police is giving a press conference.
He says around 16:00 BST this afternoon emergency services were called to support four people in difficulty in the sea.
All four were brought to shore
Three people - a man, a woman and teenage girl - have died.
Sussex Police will be giving an update shortly on the emergency in Shoreham. We will keep you updated with the key developments.
Sam Harrison
BBC News
The strip of beachfront in front of Shoreham Port remains empty as darkness falls on the Sussex coast. Locals are still not allowed close to the water. Meanwhile, a new police cordon has been set up around the scene. A significant police presence has continued here while traffic is being routed away from this section of the A259.
Emergency services were first called shortly after 15:00 BST following reports of four people getting into difficulty in the water.
The response remains ongoing this evening.
Emergency services including coastguard crews, police officers, ambulance teams and air ambulances responded after reports of four people getting into difficulty in the water.
These pictures show some of the latest activity at the scene.
Image source, Eddie MitchellPolice officers were among the agencies involved in the response near Shoreham Port
Image source, Eddie MitchellEmergency vehicles are parked close to homes near the port
Image source, Eddie MitchellTwo air ambulances were sent as part of the emergency response
Image source, Eddie MitchellPolice were among the agencies responding to the incident near Shoreham Port
A number of emergency services were deployed following reports of four people getting into difficulty in the water earlier.
Images show the response by crews, as police continue to remain on scene this evening.
Image source, Eddie MitchellAn air amublance lands as part of the emergency response
Image source, Eddie MitchellPolice officers have been conducting inquiries
Image source, Eddie MitchellMultiple ambulances were deployed to the scene, near the water's edge
Police have remained on scene as of 19:30 BST
Chrissie Reidy
Reporter, BBC South East Today
Shelley Ayres, from Shoreham, also lives opposite the beach and came home from work to find the road closed and emergency services responding to the incident near the port.
"We have never known this," she said, adding: "I'm just hoping it's nothing tragic.
"The sea has been very calm for months and months, but today it has got a lot rougher."
Image source, Chrissie Reidy / BBCShelley Ayres says she hopes the situation is "nothing tragic".
Steve Chapman says he saw multiple emergency vehicles in the area
Steve Chapman lives opposite the beach and says he came home from work but wasn't able to get to his road "because it was cordoned off".
He says he saw numerous helicopters and emergency vehicles.
"There were all sorts of rumours flying around, it was very upsetting," he says.
"All I can say is that I'm just praying for the families."
Chrissie Reidy
Reporter, BBC South East Today
We have been speaking to Shirley Pumfrey, a resident who lives near the harbour mouth.
She says she initially saw a few ambulances before more and more arrived, and then the helicopters landed on the beach.
"I have never seen them do that. The whole road was just full of emergency services," she says.
"It was horrific and quite scary to see that many."
Image source, Chrissie Reidy / BBCShirley Pumfrey lives opposite the beach and saw emergency services arriving
Image source, Eddie MitchellIf you're just joining us, here's what you need to know about a large scale response by emergency crews near Shoreham port, in Sussex.
Emergency services say they were called at around 15:00 BST to an incident after reports of four people getting into difficulty in the water.
Police say the incident remains ongoing, while Tom Rutland, the Labour MP for East Worthing and Shoreham, has urged people to "stay clear of the area".
Helicopter footage above Shoreham Harbour shows the size of the emergency response, with coastguard helicopters and other search and rescue vehicles involved, as South East Coast Ambulance Service say a number of ambulances are on the scene.
The BBC's Helena Wilkinson reports it's "very clear that it is a massive emergency service response with a number of agencies supporting the operation".
But we do not know the difficulty the four people are in, or their current condition.
Meanwhile eyewitness Pete Book describes a scene of emergency vehicles "converging on the area".
Stick with us as we continue to bring you the latest updates.
Image source, Eddie MitchellCallum French
Reporting from Shoreham
A number of vehicles have left the scene now but the road is still cordoned off and a short while ago there were still seven or eight ambulances in the area.
I live in the area and it kicked off at about 15:00 BST when I heard helicopters circling.
It's certainly one of the biggest emergency service responses that I have seen in a long time.