Emergency response enters its fifth hourpublished at 21:13 BST
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 are responding in Shoreham, Sussex, after reports of four people getting into difficulty in the water
They were called at around 15:00 BST to the incident near Shoreham port - here is what we know
Police have urged people to stay away from the area - a number of ambulances, a coastguard helicopter and an RNLI lifeboat were among the emergency services deployed to the scene
Our reporter on the scene says a number of vehicles have since left the scene but the road is still cordoned off
Pictures show numerous ambulances and a coastguard helicopter near the water's edge
Edited by Laura Sonier, with reporting from Patrick Barlow
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.
A spokesperson for Shoreham Port says it is "working with multiple agencies regarding this incident", which emergency services were called to at about 15:00 BST.
It added that it "would urge the public to avoid the area".
Kingston Beach, where the incident is taking place, is a short distance from Shoreham Port on the West Sussex seafront, near Shoreham-by-Sea.
The town is about a 20-minute drive away from Brighton.

James Kelly
BBC News
We've been hearing from a nearby resident, Pete Book, who says he was "walking home from the pub" when he "saw and heard the Coastguard helicopter circling over the lifeboat station on the beach".
"As I neared home, a yellow air ambulance helicopter landed. There were a lot of ambulances, Coastguard and police vehicles converging on the area, and the coast road was closed," he says.
Book adds: "An orange-and-white air ambulance then landed, and the Coastguard helicopter flew off."
He says the road is still closed, and there are still "lots of emergency responders and helicopters at the scene".
"The lifeboat had also launched and was being returned to the station."
The A259 is closed in both directions due to the emergency services incident, between New Road and Kingston Lane.
The street is a main commuter road between Brighton, Shoreham and Worthing on the South East coast, and further into West Sussex.
Helicopter footage above Shoreham Harbour shows the size of the emergency response after services were deployed following reports of four people getting into difficulty in the water earlier this afternoon.
A number of ambulances are on the scene, along with several police vehicles.


Tom Rutland, the Labour MP for East Worthing and Shoreham, has urged people to "stay clear of the area around Shoreham Fort and Kingston Beach as emergency services respond to reports of several people in difficulty in the water there".
In a post on X, he says that "the incident remains ongoing".
Helena Wilkinson
Speaking to BBC Radio Sussex
It is very clear that this is a huge emergency operation taking place in Shoreham.
We have had a number of statements from emergency services including Sussex Police. It is very clear that it is a massive emergency service response with a number of agencies supporting the operation.
What we don't know is the kind of difficulty the four people are in, and no information has been released in terms of how far out to sea they were, or the current condition they are in.
A spokesperson for the Air Ambulance Charity in Kent, Surrey and Sussex (AAKSS) says it sent both of its helicopters and critical care team to the scene of the incident today "as part of the coordinated emergency response".
As a reminder, emergency services were called at about 15:00 BST.

There is a large emergency services presence on the seafront in Shoreham, West Sussex, this afternoon after four people got into difficulty in the water.
Information is still coming in, here's a look at what we know - and what we don't - at the moment.
What is unclear at the moment is what kind of difficulty the four people are in. No information has been released on how far out to sea they are, if they have any sort of vessels or floatation aids with them, or the current condition any of them are in.
We will continue to keep you updated throughout the evening.
The Coastguard says it "responded to an incident reported at Shoreham at about 2.45pm".
"An HM Coastguard helicopter was sent as well as Littlehampton, Shoreham and Newhaven Coastguard Rescue Teams, and an RNLI lifeboat from Shoreham," the spokesperson adds.
"Sussex Police and South East Coast Ambulance Service also attended."
Image source, Eddie MitchellBBC News' Callum French is in the area and says he saw helicopters flying overhead and ambulances heading towards Shoreham Port.
"There was a lot of traffic and they closed the road for a bit," he said. "It's the biggest turnout I have seen in the last few years here."
He added that, despite recent warm weather, the sea conditions have been "pretty rough" due to the high winds.

The incident took place in Shoreham Harbour
We now have more from South East Coast Ambulance Service, which says it was called to "reports of four people in need of medical attention after getting into difficulty in the water near Shoreham Harbour".
"We were called shortly after 15:00 BST and have a number of ambulance resources at the scene," it added.