A four-year-old boy suffered life-threatening injuries Thursday night after a car crash in Waco.

Police said it happened at South 18th and Webster around 8:30 p.m.

When emergency responders arrived, they discovered a woman in the car had initially been unconscious but was revived. She was taken to Baylor, Scott and White Hillcrest.

The boy had serious head trauma, according to Waco Police, and was taken to McLane Children's Hospital.

Police said it appeared the child was either not restrained or improperly restrained because there was no booster seat in the vehicle.

According to the National Highway Transportation Safety Administration, children between the ages of 4 and 7 should sit in a forward-facing car seat with a harness and tether until he or she reaches the top height or weight limit allowed by the car seat’s manufacturer.

Once the child outgrows the forward-facing car seat with a harness, children should sit in a booster seat, but still in the back seat.

For more information on car seat safety click here.