Paramedics were called to the scene of the two-car accident about 2pm near the Albion Park Rail McDonalds.

The two-year-old had facial and possible spinal injuries likely after hitting his head on the back of the front seat,

Read more: Two trapped after truck and car crash at Bomaderry

The two-year-old boy was airlifted to Sydney Children's Hospital, Randwick in a critical condition.

The driver, a woman aged in her 50s, was suffering chest injuries.

The third passenger, a young child, was uninjured, while the driver of the other car was also not hurt.

The woman and uninjured child were transported by road to Wollongong Hospital.

Motorists were advised to avoid the Princes Highway in Albion Park Rail.

All southbound lanes and one northbound lane of the highway were closed until shortly before 7pm.

Crash investigators were on the scene to determine the cause of the collision.

Traffic was heavy in both directions so motorists were advised to allow plenty of extra travel time.

Meanwhile, the Princes Highway was closed further south due to a two truck crash at Jaspers Brush.

The highway reopened between Berry and Bomaderry, shortly after 6.30pm.

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