Mum and daughter who died at beach were trying to save boy, 7

Samiha and Shally Rahman were on a holiday trip to West Mersea when the tragedy unfolded

A woman and her 15-year-old daughter who died after getting into difficulty in the water on the Essex coast were trying to help a seven-year-old boy, police have said.

The child remains in a critical condition in hospital after the incident at West Mersea near Colchester on Wednesday evening. Three others were taken to hospital.

The victims have been named by a family member as Shally Rahman, 41, and teenager Samiha Rahman. Police said all the people involved knew each other.

Shally's brother-in-law Matiur Rahman said the family was enjoying a seaside holiday when a "big wave came and took them".

"My whole family, we are, like, speechless," said Matiur Rahman, who used to live in Bradford, but spoke to the BBC from Bangladesh.

"We are very shocked. We can't explain [what has happened]."

He said his niece was a "very, very good person" and his sister-in-law was "a very helpful person".

Mother and daughter who died at Essex beach were trying to help boy, police believe

Local people have described bystanders rushing to the water to help, including teenagers who worked at the nearby Seaview Beach Diner, and at least one off-duty paramedic who was walking their dog.

Prime Minister Andy Burnham, speaking on a visit to Harlow in Essex, described the deaths as "very sad" and thanked emergency services for their efforts.

Local people praised the professionalism and speed of emergency response teams, including the RNLI

Essex Police - which was called by the ambulance service at 17:35 BST to the water near Seaview Avenue - said the victims were from London.

"At this stage we believe they were trying to help a seven-year-old boy who had got into difficulties," said Det Ch Insp Al Pitcher.

He said officers had been speaking to "dozens" of witnesses to establish the circumstances leading up to the tragedy, and asked anyone else with information to contact the force.

The detective thanked first responders who worked "tirelessly" to try saving their lives.

The East of England Ambulance Service said the deceased could not be resuscitated "despite best efforts". A spokesperson said four more people in total were taken to hospital, including one by air ambulance.

Rita Coombs said one man walked away from the scene unable to talk about what he had witnessed

Rita Coombs, one of the nearby residents who laid flowers at the beach, described the events as "absolutely horrific".

One man "couldn't speak" about what he had witnessed after returning from the scene, she added.