A man and a toddler have been killed and a woman is fighting for her life after a three-vehicle crash in Sydney's west overnight.
Emergency services were called to the intersection of Mamre and Abbotts roads at Kemps Creek at about 10.40pm.
They found a small sedan and a van had crashed head-on.
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Investigators were told the sedan and a ute had collided immediately before, following which the sedan and the van slammed into each other.
A man in the sedan's front passenger seat died at the scene, while a 25-year-old woman and her 15-month-old son sitting in the back of the car were critically injured.
Both were taken to hospital, where the little boy later died.
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The 21-year-old L-plate driver of the sedan and the 45-year-old man driving the van suffered "relatively minor" injuries, police said.
Both men were taken to hospital for assessment and mandatory testing.
The male driver of the ute was unharmed.
Traffic restrictions remain in place on the scene this morning as the investigation continues.
Anybody with information or relevant footage is urged to contact Crime Stoppers online or on 1800 333 000.
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