The coastguard is searching for a missing person in the water after a rescue operation in East Sussex saw two casualties transferred to hospital.
One person was taken to hospital by helicopter while another was transported by ambulance after the incident at Camber Sands, the Maritime and Coastguard Agency said.
Rescue teams from Dungeness and Rye, Coastguard rescue helicopters from Lydd and Solent, Rye RNLI lifeboat, beach lifeguards and police are searching for a missing person last seen in the water.
A spokesman for South East Coast Ambulance Service confirmed two patients had been rescued from the water and taken to William Harvey hospital in Ashford, having been resuscitated.
He said both are in a life-threatening condition.
The ambulance service was called at about 12.40pm to reports a number of people had got into difficulty in the water.
Sussex police tweeted: "We've been working with RNLI & Coastguard at #Camber 3 people have got into difficulty in the sea. 2 flown to hospital, 1 man still missing."
Police dismissed reports the men had been stung by jellyfish.
The force tweeted: "To clarify the men got into difficulty in the sea at #Camber & were not stung by jellyfish as is being reported in some places."