An 11-year-old boy who is missing and feared dead after entering a South Yorkshire river has been named as Mackenzie Swift.

The boy has not been seen since Saturday, May 30, when it is believed he entered the River Don in Mexborough.

A major search operation was launched to try and find him, including firefighters, mountain rescue and an underwater search team.

Police said they have now had the 'heartbreaking conversation' with his family, that it is unlikely that Mackenzie could have survived in the water for this length of time.

They said they have no indication that he got out of the water on Saturday.

South Yorkshire Police said they will continue to search for Mackenzie. 

In Norfolk, a 44-year-old man who died in the River Yare at Surlingham has also been named as Greg Howes. 

At least 17 people, mostly children and teenagers, have died in open water in the last 10 days.

Doncaster District Commander, Chief Superintendent Pete Thorp, said: 'We will continue to do everything in our power to find Mackenzie and to support his family through this incredibly difficult time. They truly are living every parent's worst nightmare.

'We are utilising a range of specialist resources and organisations from across the region. 

'Officers will remain at the search site tonight and further operational activity will resume at first light tomorrow morning.

'I understand members of the public are desperate to help, but I must ask that you leave this work to the professional search teams. 

'Please do not put yourselves or others in danger by searching in and around water, and if asked to leave by officers, please understand this is for your own safety and to ensure our efforts focus solely on finding Mackenzie.

'The thoughts of all those involved in the extensive search operation remain with Mackenzie and his family.'

The family of Greg Howes, who died in the Norfolk Broads on Saturday afternoon, have urged people to take care on the water.

In a tribute, his family said he had been 'dearly loved by his family and loved spending time on the Norfolk Broads'.

'At this sad time, his family would like to urge the public to take care and consider their safety when taking part in activities on the water on the Broads,' the statement added.

Earlier today, the first picture of a 16-year-old girl who died after getting into difficulty in open water was released.

Lillianna Tomlinson died after entering the River Tame close to Kingsbury Water Park in north Warwickshire last Monday.

Her 'devastated' family paid tribute to her in a statement released through Warwickshire Police today. 

The family said: 'We're deeply saddened to be writing that Lillianna's life has been taken in the most tragic way.

'Our family is completely devastated and will be forever heartbroken.

'We would like to take a moment to sincerely thank our community for the love, compassion and support that has been shown to us, and for sharing in our grief - it means more than words can express.'

An online fundraiser set up by the mother of Lillianna's best friend describes the teenager as 'a bright, kind, and caring young girl who touched the lives of everyone who knew her.'

Yesterday, a 13-year-old girl died after being pulled out of the River Wharfe in the Yorkshire Dales National Park.

And on Saturday, a woman died after entering the sea to try to rescue her dog in Thornton Cleveleys, Lancashire.

The woman and a man, both in their 60s, were pulled from the ocean near Fleetwood Beach Café by the coastguard before being handed to paramedics.

Tragically, the woman was pronounced dead in hospital while the man remains in a critical condition. The dog was 'recovered safe and well'. 

Last Friday, Police Scotland named a 16-year-old who died after getting into difficulty in the water in Stirlingshire as Charlie Noble.

And last Wednesday, the body of 14-year-old Baltazar L'Qui was found in the River Thames, while another teenage boy was found in a pond in Swanscombe, Kent.

The same day, a missing teenage boy's body was found in a lake near Blackwater in Hampshire after he went missing while swimming.

A body was also found at Hawley Lake in Hampshire after he went missing while swimming. Formal identification has yet to take place, but his family has been informed.

Last Tuesday, two boys were found dead, including 17-year-old David Junior-Tita from Crewe, who died at Pickmere Lake in Cheshire.

Junior Slater, 12, also died after getting into difficulty in the River Ribble in Lancashire.

That day, police also recovered the body of a drowned 16-year-old boy from Sheffield who died in a Rotherham lake after going missing while swimming.

Muhammad Secka, who had drowned the previous day, was described as a 'lovely, kind boy' who dreamed of becoming a doctor.

A 15-year-old girl also died in hospital on Saturday after getting into difficulty in the sea off the coast of Merseyside on Bank Holiday Monday.

Chiedza Nyanjowa, from Cheshire, was taken to Alder Hey Children's Hospital after swimming at Formby beach, Merseyside Police said.

There were four more deaths on Monday as temperatures reached 34.8C at Kew Gardens and broke the record for the hottest-ever May day.

Among them was 13-year-old Reco Puttock, who was pronounced dead after being found in Leadbeater Dam in Halifax, West Yorkshire.

The same day 16-year-old Lillianna Tomlinson was found dead at Warwickshire's Kingsbury Water Park.

Heroic grandfather Phil Crow, 68, also died after suffering a cardiac arrest when he ran out to the sea trying to rescue his wife and granddaughter when they got into difficulty at Tregirls Beach in Padstow, Cornwall.

On Sunday, an unnamed 72-year-old woman died off West Angle Beach in Pembrokeshire. In Lincoln that day 15-year-old Declan Sawyer also died after getting into difficulty at Swanholme Lakes.

On Friday, Police Scotland named a 16-year-old who died after getting into difficulty in the water in Stirlingshire as Charlie Noble. 

The body of 66-year-old Stephen Faulkner was found in Tonypandy, Rhondda Cynon Taf on Thursday, following a five-day search. 

A 19-year-old man, who had been at the lake with friends, was recovered from the water at Balderton Lake, off Heron Way in New Balderton, on Thursday afternoon.

On Saturday, Nottinghamshire Police said the man had not survived, adding that his family has been informed and were being supported by specialist officers.

He had not been seen since Friday, prompting a large-scale search operation involving fire, ambulance, air ambulance, coastguard personnel and other search teams.

Temperatures have since dropped towards the average for the time of year following the heatwave.

Forecasters said the first day of June would feel 'more like spring or autumn', with thunderstorms and cooler temperatures expected.

Tuesday was the hottest May day on record for both England and Wales, with 35.1C measured at Kew Gardens and 32.9C at Cardiff Bute Park.

Met Office meteorologist Rebecca Mitchell, said the heatwave was 'over'.

She added: 'Ironically, it's the first week of meteorological summer starting (on Monday), but it will be feeling much more like spring or autumn and a big contrast to the heatwave.'

Of this week's weather, she said there was a 'big change on the way', including rain, possible thunderstorms and strengthening winds.

'The other part of the story is the temperatures will be much lower compared to the week just gone,' she said.

'They'll be around average for the time of year, which typically is around 17 to 19 degrees in the north and around 18 to 21 degrees in the south, so about 14 degrees lower in some places compared to the previous week.'