Forensic police are scouring a house in Brisbane's south where a 10-year-old boy was found dead in a bedroom.

His body was found by ambulance officers in a house on Mt Gravatt-Capalaba Road at Mackenzie just before 5:00pm on Sunday.

Police Inspector Daniel Bragg said a woman, believed to be the boy's mother, was the only person at home at the time and was taken to hospital for an unrelated medical condition.

The house has been cordoned off and declared a crime scene.

"We have got a large number of detectives, we have got scenes of crime here, we are talking to witnesses, we have a deceased child, we have a number of witnesses," Inspector Bragg said.

"We don't know what has occurred here as yet."

Police were hoping to interview the woman overnight but are yet to speak to her.

They said a post-mortem examination is expected to be completed today.

Neighbours said the boy lived in the house with his parents and several siblings.

They said the family was never rowdy or "out of the ordinary".