The crash Friday sent 20 people to the hospital, including the driver and King.
King was thrown through the windshield and airlifted to UAB Hospital, where she was listed in serious condition, officials said.
"She jumped over and pulled the wheel," said Alix Romano, a Bryan Elementary School fifth-grader who sat near the front of the bus.
The bus, owned by Adventure Bus Charter & Tours Inc. of Sumiton, was headed north to Chattanooga's Tennessee Aquarium. It was the lead bus in a caravan with two other charter buses hired by the Morris school and cars driven by chaperones.
The bus sideswiped 200 feet of guardrail before it came to rest upside down in a drainage ditch about 30 miles northeast of Birmingham.
Wreckers had to lift the bus off one child, Springville Fire Chief Richard Harvey said. The wreck is being investigated by Alabama State Troopers.