Witnesses say a heroic day-tripper managed to haul two children back to shore during an incident where a mother and daughter drowned.
Beverly Smit, 60, described the unnamed rescuer swimming out to sea three times as the tragedy unfolded in West Mersea, near Colchester, on Wednesday evening.
Shally Rahman, 41, and Samiha Rahman, 15, were trying to rescue a seven-year-old boy from the water when they got into difficulty and died.
Essex Police said the group, from Barking, east London, were all related to each other and the boy remained in hospital, fighting for his life.
Recalling the moment the “Good Samaritan” sprung into action, Smit said: “They were calling for help and the children and adults were out there.
“He swam out, I think, three times. Two of the children he brought back were not in good condition.
“It’s not an easy swim when the tide’s coming in – you’re swimming against the tide. The water [on Wednesday] was particularly quite cold.”