A teenage girl and a woman in her 40s have died after getting into difficulty in the water off the Essex coast, police have said. One person is also in hospital in a “serious condition” following the incident near Seaview Avenue in West Mersea, Colchester, at 5:35pm on Wednesday evening. Police said they believe those involved in the incident were known to each other.The West Mersea Coastguard Rescue Team said on Facebook early on Thursday that they had been called to a “tragic incident” on the beach.Pictures show a huge emergency services presence on West Mersea beach in Essex on Wednesday evening, and a cordon remains in place on Thursday morning.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.”They 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.”Local MP Sir Bernard Jenkin said he is "sad and very shocked" about the incident in a statement to the BBC."We don't think of West Mersea Beach as a dangerous beach,” he said."I mean, there are tidal currents but thousands of people use it as this time of year and generally feels like a very safe place.”Speaking before the police confirmed two deaths, Carl Powling, Conservative councillor for Mersea and Pyefleet, told BBC Essex local residents were the first on the scene following the incident."It's definitely a tragic incident and it does highlight the dangers of the tidal area we live in and the sea and what can happen,” he added.