The death of a Rotorua child is believed to be from a falling object.

Police have said the sudden death of a child in the Rotorua suburb of Western Heights on Thursday is not being treated as suspicious.

Police were called to the property on Brookland Rd late Thursday morning and said in a statement that enquiries were continuing 'to get an understanding of the events leading up to the incident”.

The child's older sibling remains in a serious but stable condition in Auckland's Starship Children's Hospital.

Police have referred the incident to the coroner and will continue to make enquiries in relation to the child's death on behalf of the coroner.

"Police would like to extend our sincere condolences to the child's family at this difficult time," a spokesperson says.

A witness who 'heard a mother wailing” and rushed into the house to offer first aid said he was told something heavy had fallen on a baby, before the family rushed both children to hospital.

'I was walking back home from the shop and I heard a mother wailing and I ran in and told them I was a trained first-aider... I asked if there was any way I could help,” the witness says.

He thought the baby was about two years old, and said he had spoken to police about what he saw.

He said the baby was not moving when he arrived.

"I couldn't really do much.”

Matthew Martin/Stuff