The boy was a passenger in a 2008 Honda Pilot driven by Casey Guidry of Forked Island.
Guidry was heading north on La. 35 when for unknown reasons she may have turned into the path of the 18-wheeler driven by Harold Richard, 51, of Church Point.
It appeared Guidry was turning left onto Liberty Farm Road, located south of Kaplan.
The 18-wheeler pushed her Pilot along La. 35 for about 100 yards when it came to stop after they both slammed into a light pole.
The front of the truck smashed into the vehicle, killing the boy. Guidry was transported to a nearby hospital by AirMed.
The 18-wheeler was hauling oil and it did not look like any had leaked out due to the accident. It was unknown if the driver of the 18-wheeler was injured.