(CNN)When the box truck collided with the school bus, it left the back of the bus crumpled like a piece of paper.
But what happened next was remarkable.
The driver of the truck jumped out, helped pull students out, then collapsed, authorities said. He later died.
"He must've been running on adrenaline, and his body gave out," said Cpl. Shane Copeland with the Georgia State Patrol. "He was pretty much done by that point."
The incident happened Wednesday afternoon.
The school bus was making its normal stops just outside the city of Alma in Bacon County, Georgia when it was rear-ended by a box truck.
"The impact sent the back of the box truck into the air, leaving metal scattered across the highway," Copeland said.
The truck driver, 25-year-old Johnathon Grayer, jumped out and rushed on to the school bus, Copeland said.
Footage from the bus' surveillance camera showed him lift seats off children who were pinned underneath, he said. After he collapsed, Grayer was taken to a hospital -- where he later died.
Ten children and the bus driver were also taken to hospital, but their injuries were not life-threatening.