A body has been found in the search for an 11-year-old boy who went missing after entering the River Don in South Yorkshire on Saturday.

Mackenzie Swift entered the river in Mexborough at around 8pm and failed to emerge, prompting a police search.

Officers announced on Tuesday morning that a body had been found during their search of the river. A spokesperson said formal identification had yet to take place but Mackenzie’s family had been informed and had been offered specialist support.

Ch Supt Pete Thorp, the South Yorkshire police district commander for Doncaster, said: “First and foremost, on behalf of all who have been involved in the operation to find Mackenzie since Saturday, I send deepest sympathies to his family and friends. Losing a child is every parent’s worst nightmare and I know the impact this news will have on the wider community and particularly Mackenzie’s school.

“I would also like to thank the local community, who enabled us to conduct our search and recovery with very few onlookers and cameras, to give Mackenzie and his family the dignity they deserve. Not only for that but also for the offers of assistance – we knew we had many members of the public willing to do anything they could to help.”

Police conducted the search alongside South Yorkshire fire and rescue service, Woodhead mountain rescue and an underwater search team, and Thorp expressed his gratitude to all involved.

There were at least 15 water-related deaths during the record-breaking hot spell in the UK last month. They included a 13-year-old girl who died after getting into difficulty in the River Wharfe in Burnsall, near Skipton, North Yorkshire, on Sunday evening; a 15-year-old from Cheshire who died in hospital after being rescued off the coast of Merseyside on bank holiday Monday; and a woman in her 60s who died trying to rescue a dog from the sea off Thornton-Cleveleys, Lancashire, on Saturday. A man in his 60s who tried to help rescue the dog remains in critical condition.

People in the area where Swift went missing have said the part of the river where he entered was known to be dangerous and that a child could easily get swept away.

Water safety experts have warned about the dangers of outdoor swimming after the spate of deaths. Many fatalities are thought to be triggered by cold water shock as the water can remain very cold even when the air temperature soars.

Dr Heather Massey, an associate professor in extreme environments and physiology at the University of Portsmouth, said: “Unfortunately, this is something we see every year. It’s a known problem when the air temperature increases rapidly but the water is still very cold. At this time of year, it hasn’t had time to warm up.”