The mother and daughter who died after getting into difficulty in the water off the Essex coast have been named as Shally Rahman, 42, and Samiha Rahman, 15.
A seven-year-old boy is also in a serious condition in hospital, the family told the BBC.
Emergency services were called to West Mersea beach near Colchester at 5:35pm on Wednesday evening. Witnesses reported seeing a group of people standing on a seabank as the tide came in, and described them “calling for help”.
Paramedics said one patient was transported by air to hospital, and a further three patients were transported by road to hospital.
A cordon remained at the scene on Thursday as the town reeled from the tragedy.
A family friend of the deceased, Mishba Uddin, of Colchester, told the press that the families involved in the incident had come down for the day from east London and Barking.
He said the father is a doctor from Bangladesh heritage, but he “only knows the grandfather very well”.
“They are a very nice and likeable family,” added Mr Uddin.
Beach hut owner Beverly Smit, 60, said she heard the emergency response on Wednesday night and went to see what was going on.
“By that time they were re-sussing the person on the beach, the helicopters were still in the fields,” said Ms Smit, who works for a local dentist.
She said that she spoke to a day tripper who had rented a neighbouring beach hut and had tried to help.
“It’s not an easy swim when the tide’s coming in, you’re swimming against the tide, the water yesterday was particularly quite cold.”
Another woman, who did not give her name, said the incident at West Mersea happened at high tide.
Emergency services had urged people to avoid part of the beach in Essex after what the coastguard rescue team described as a “tragic incident”.
Detective Chief Inspector Al Pitcher said: “Today, our thoughts remain with the family members who are coming to terms with their loss.
“We are grateful to the people who have already spoken to us and helped with our enquiries. We would ask anyone who was at the beach at the time, and who has not yet spoken with officers, to please get in touch, to help us understand what happened.”
He added: ”At this stage of our enquiries, we believe those involved in the incident knew each other. Anyone who was in the area at the time and has information or footage which may assist our investigation is asked to contact us on 101 and quote incident 1090.”
A spokesperson for Park Holidays UK, which owns West Mersea Holiday Park adjoining West Mersea beach, told The Independent that everyone at the park had been devastated by news of the tragedy, and that the company extended its heartfelt sympathy to the family and friends of all those involved.
The spokesperson said the family associated with the incident were not staying as guests on the park.
