Police are not looking for anyone else in connection with the death of the man, 41, and boy.
A man and five-year-old boy have been found dead in a house in Leicester.
Police were called to an address in Hopyard Close at 21:00 BST on Monday after the man, 41, and boy were found unconscious.
East Midlands Ambulance Service and an air ambulance also attended but the pair were pronounced dead at the scene.
Leicestershire Police is carrying out an investigation into the deaths, but officers are not looking for anyone else at this stage.
A cordon remains in place while inquiries continue.
Det Ch Insp Mark Sinski, from the East Midlands Special Operations Unit major crime team, said: “Detectives are working to understand what happened inside the address last night.
“I can reassure people that there is no risk to the public.”
He added the families of the man and boy were being supported by officers.
Alan Potter, 75, who lives next door, told the BBC he heard the boy “running about” – as he normally would before bed – at about 18:00 or 19:00.
He said emergency services arrived from about 20:30, “dashing in and out of the house”.
Mr Potter added the man’s cousin also lived at the address.
“It’s awful – I wish it hadn’t [happened], but can’t turn the clock back,” he said.
He paid tribute to the five-year-old’s “beautiful” personality, adding that he used to buy him presents at Easter and Christmas.
Mr Potter’s wife Carole, 70, said they were “great friends” with the boy’s mother, adding that they treated him “like he was my grandson”.
“I didn’t know anything until his mum came knocking on the door really loud,” she said.
“I’m just so upset about it. It’s tragic. I just can’t believe that’s happened on our doorstep.”
Neighbour Wayne Hurst, 51, described seeing a “load of ambulances” and police cars on Monday night.
“I’m a bit shocked and scared, I can’t say no more, really. I’m just shocked,” he said.
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