One person remains missing following a dramatic rescue which saw pier staff hanging onto ropes as they tried to keep stricken swimmers afloat.
The coastguard has confirmed five people were pulled from the water at Clacton, in Essex, after getting into difficulties.
One man is still missing and a rescue helicopter, RNLI lifeboat, coastguard rescue teams and the Clacton beach patrol are all involved in the search.
The five rescued swimmers - one female and the rest male - were taken to Colchester Hospital.
Nigel Brown, from Clacton Pier, said a group of between eight and 10 swimmers - some wearing shorts and t-shirts - had entered the water about 100 yards to the east of the pier just before 11am.
While some remained close to the beach, others ventured further into the sea and appeared to get caught up in the tide and currents which swept them west under the pier.
Staff threw safety rings down and held onto the ropes.
"The first one scene was the beach patrol jet ski," he said. "He picked up a casualty and two lifeboats picked up another three.
"They were shouting about another person being missing. Soon after we had police, fire, ambulance, coastguard and the helicopter carrying out the search for the missing person."
Mr Brown said he had been told there was one female in the group and the rest were male. Those he saw were in their teens or early 20s and a number were wearing shots and t-shirts in the water.
Praising pier staff, some of whom were also in their teens, who clung onto the ropes to hold the swimmers steady.
"I think it's fair to say some of those could have been in serious danger had they not got the safety rings and been held on to," he said.
Shop worker Toni Cloke, who had spent the day at the seafront, said police asked beachgoers to clear the beach as emergency services took a number of people away.
The 47-year-old, of Clacton-on-Sea, said: “I saw four or five people get taken in (by emergency services) then we got asked to clear the beach. I would say they were holidaymakers.”
EEAS said: “A large response, including two ambulances, four Hazardous Area Response Team Vehicles and Essex and Herts Air Ambulance, was sent to Clacton Beach this morning following reports of a number of people in difficulty in the water.
“Five patients were assessed at the scene. One male and one female were transported to Colchester Hospital for further assessment and care.
“Three males were discharged at the scene. Crews remain on-site as one male remains unaccounted for.”
Essex Police said: “We’re on the scene assisting emergency services colleagues with a serious and ongoing incident close to Clacton Pier.
“There is a significant emergency services presence in the area while the incident is being dealt with."
Clacton Pier has been closed, on advice from emergency services, and the beaches either side have been evacuated.
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