Police said the body was found at approximately 8.30am this morning.
Wayne Bolton went with his son, Finley, four, to pay his respects.
He said the first he heard was the helicopter being used to search for the boy on Sunday night.
Mr Bolton said: "We are not friends with the family, but it's tragic what's happened and it just makes you appreciate what you have.
"I can't begin to imagine what that family are going through.
"It was such a tragic accident, hopefully, and we just want to show support for the family and to be fair the whole community has turned up. It's shocked everyone and everyone is in bits and luckily, in an area like this, everyone comes together and we all help each other."
Detective Inspector Victoria Short leading the investigation said: “We deployed our full resources with officers searching throughout the night to find Conley and we are deeply saddened by this tragic development.
“While it is early in the investigation, the death is being treated as unexplained and a post-mortem examination will take place in due course.
“Our thoughts remain with Conley's family and friends at this very difficult time.”
Conley was last seen in Locke Park where he had gone to play with friends at around 6pm. He is believed to have left the park at around 8pm but failed to return home to Underwood Avenue in Worsbrough afterwards. He was reported missing shortly after.
Around 50 police officers were reportedly deployed in the search for the missing boy overnight, according to the BBC, while local residents tweeted seeing a helicopter joining the search effort.
Detectives had this morning cordoned off the building site as many had taken to social media to share in the search for Conley. The boy's school made a public appeal for information about his disappearance on Facebook.
It came as his school made a public appeal for information about his disappearance.
Nichola Thorpe, headteacher of Worsbrough Bank End Primary School, wrote on Facebook: "Dear families, can you help?
"Conley is missing since last night (Sunday) and the police are looking for him. We pray that he is safe and has stayed with friends.
"Please share and spread the word to get him home safe and well."
A police spokesman said: "Formal identification of the body is yet to take place; however, it is believed to be that of Conley."