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News 4 Investigates: Guardrails

(KMOV) -- Two children are in a St. Louis hospital after the car they were in flew off Interstate 55 and over a cliff.

Their mother, Andrea Whitehead, 35, died in the crash.

There were only three people in the car; the mother and her 12-year-old son and eight-year-old daughter.

The girl is listed in critical condition and the boy is in serious condition.

A man who works near the crash site cut the children out of the car. 

The accident happened around 6:40 a.m. on Thursday near Gasconade just off I-55 in south St. Louis.

Another man who was driving behind the car on the interstate says Whitehead tried to change lanes, saw a car there, overcorrected and lost control of the vehicle.

That's when the car went over the edge and landed on its roof.

The children were trapped in the backseat of the vehicle.

One witness says this is the second accident he's seen there recently.

Family members tell News 4 that the family was on their way to swim practice.

The family is from south St. Louis.