Five people have died after being pulled from the sea at Camber Sands beach.
Emergency services were called after three people were found in need of urgent medical aid at the coast near Rye, East Sussex on Wednesday afternoon.
Beach goers were urged to stay out of the water as medics helped the men, who have yet to be identified.
It is understood reports of a person in the sea were first received at 2.10pm, a second person was then discovered in difficulty at 2.20pm and a third person was pulled form the sea 15 minutes later.
The RNLI later confirmed two more bodies had been found, bringing the total number of fatalities to five.
A search is under way for a further missing person, with two lifeboats and a helicopter combing the water off the coast.
The Lydd and Lee-on-Solent-based UK Coastguard search-and-rescue helicopters also attended the scene, along with an air ambulance.
An RNLI lifeboat from Rye and Coastguard rescue teams were also in attendance.
Natalja Taylor, 30, who was on a day-trip at Camber Sands with her husband on the hottest day of the year, said police were driving up the beach with a loud hailer calling on people to stay out of the sea.
She said: "We saw three people being pulled out of the water. I think the people who rescued them were regular people, not emergency personnel.
"Police drove on to the beach with a loudspeaker, telling people not to go into the water until further notice. They also taped off a huge chunk of the beach so no-one could get near it.”
Eyewitness Luke Russell, from Bromley, said: "The water didn’t look that bad. It looked quite calm. It looked like the tide came in quite quickly compared to last week. We had to move our stuff further up the beach twice because it came in so fast.
"They first discovered people were missing at about 12.30pm, which is when we got there. The helicopter circled the beach and came down.
"Apparently, there was a bad rip tide which dragged them out.
"The beach was really packed. There are a couple of lifeguards up there, but they don’t really have a very good vantage point. They just sit around the main entrance where the car park is.
"After we saw the first body come down the beach, they cleared out of the water and then the boats and helicopters went up and down the coast line trying to find the others.
It is the second time a serious incident has taken place recently at Camber Sands.
In July, a 19-year-old Brazilian Gustavo Silva da Cruz died after getting into difficulty while swimming in the sea.
A 35-year-old man and his 17-year-old son, not connected to Mr Da Cruz, also got into difficultly in the water.
Chief Superintendent Di Roskilly said: "We are working with Maritime and Coastguard Agency, Royal National Lifeboat Institute, South East Coast Ambulance and Rother District Council to clear the beach and encourage people to come out of the sea while we are investigating this incident.
"We are also asking people to stay away from Camber for the afternoon and evening to assist emergency services in managing this incident.
"This has been an incredibly tragic situation and very traumatic for those who were there on the beach at the time. At this stage we do not know who the men are and are doing all we can to establish their identities."
Additional reporting by Press Association
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