"I just saw the vehicle flip about three or four times and kids flying everywhere," witness Tammy Hall told WAFB-TV. "It looked to be about 10 to 11 kids out of the car. And everyone started stopping, and we went to get her, and you could tell the driver was dead instantly."
The van didn't have enough seatbelts for the 13, Louisiana State Police spokesman Russell Graham said. The driver, who was killed, and a front-seat passenger, appeared to have been the only ones wearing seatbelts.
The crash occurred after the front tire blew out on the driver's side, Lt. Doug Cain said. The van then hit the delivery truck traveling in the same direction, rolled about 200 feet across the median and landed on its tires in the oncoming lanes. No other vehicles were involved.
"The Louisiana Legislature just passed a law making it mandatory to wear seatbelts in both the front and back seats," Graham said. "This is a good illustration of why they did."
The 10 survivors were in critical condition Saturday afternoon at two Baton Rouge hospitals, Graham said.
Alcohol was not suspected in the crash, police said.
The driver of the truck managed to steer to the side of the road and was not injured.
The interstate was closed in both directions for about three hours Saturday afternoon.
No identities were immediately released. It wasn't immediately clear why the van full of children was on the highway.