A two-year-old boy is in a critical condition after nearly drowning in a dam on a north-west Sydney property.

Shortly after 10:30am, emergency services were called to a Maraylya property after a toddler was pulled unconscious from the water.

NSW Ambulance Inspector Greg Marshall was first on the scene and took over performing CPR from the family.

He told Jim Wilson the boy was “in a very, very critical condition” on his arrival to The Children’s Hospital at Westmead.

“It’s an incredibly tragic scene that we’re faced with.

“It’s every parent’s worst nightmare, myself included.

“It really does only take a moment … especially in these hot summer months: please everyone, be careful in the water.”

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Image: Nine News