Boy, two, saved from house fire in Sydney's west

A toddler has narrowly escaped serious injury after a house fire in Sydney's west.

The boy was playing alone in his bedroom, when a mattress ignited, trapping him on the second storey of the home in Fairfield Heights.

First responders played Bluey on their phones to help calm the two-year-old boy.

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He was pulled from an upstairs bedroom at 6pm last night as the bedding around him started to burn.

"The toddler was covered from top to toe with soot," NSW Fire and Rescue Superintendent, Adam Dewberry said.

"They could actually hear the screaming and the crying out."

The toddler was in a serious condition suffering smoke inhalation.

He was administered oxygen on the street.

The boy's mother and two other children got out of the Stanbrook Street property.

Police and fire investigators are considering whether an electrical fault triggered the emergency, or whether the child was playing with a lighter.

The boy spent the night at the children's hospital in Westmead in a stable condition.

Investigators say it's a strong reminder to keep dangerous objects out of reach.