"We were driving and heard a big bang and smoke, so we got out of the car to see what had happened. One half of the car was on the right side of the road and the other half on the other side," she told The Daily Telegraph.
"The little girl kept saying her back hurt so I got her to sit down and tried to settle her down."
Ms Currie also described seeing the policeman, Sergeant Steve Underhill, arrive at the crash scene.
"He was speechless, he was so shocked and upset. He wanted to know what had happened."
She said the officer tried desperately to help but was suffering from shock.
The car was being driven by an 18-year-old woman.
Unconfirmed reports suggested she was the children's babysitter, Fairfax reported.
The 2-year-old was "conscious and responsive" and making a "remarkable recovery", a NSW police spokesman said yesterday.
She was rushed to Lady Cilento Children's Hospital in Brisbane in a critical condition.
The girls were reportedly travelling in a car with an 18-year-old woman, who was driving.
The woman suffered spinal injuries, while an 8-year-old girl was taken to hospital with minor injuries.
"Initial inquiries suggest two vehicles collided, with one vehicle splitting in two as a result of the impact," police told news.com.au.
An elderly man who was the sole occupant of the second car was uninjured but taken to hospital for observation.
"It's an absolute tragedy that someone so young has been lost today," Acting Assistant Commissioner John Hartley said.
"With the increase of traffic on the road over the holiday period I am appealing to road users to drive safely and be vigilant when travelling."
The relationship between the girls was not known, but police said the child who died was not related to the young driver.
NSW Police Major Collision Squad were investigating the Casino accident and a report would be prepared for the coroner.
