"This kid did some quick thinking," said Larry Gray, a fire department spokesman.
The bus, carrying 27 children in kindergarten through seventh grade, crashed into a bridge support pillar after rolling away from the gas station across the street from Progressive Field, home of the Cleveland Indians.
The children jumped out of the side door and landed in the street, said the gas station manager, Conner Strickland. "I'm surprised none of them got hit. There was a lot of traffic," he said.
Strickland said he saw the bus rolling and banged on the restroom to alert the driver. Then he and another employee chased the bus down the hill.
Fire officials took 15 children to hospitals with mostly minor injuries, said Larry Gray, a fire department spokesman. None of the injuries were life-threatening, he said.
The driver the was taken to a hospital with chest pains, Gray said.
The driver and firefighters from a station at the top of the hill helped the children off the bus. Most just had bumps and bruises, Strickland said. "I thought it was going to be worse than that," he said.
The bus was carrying students to Arts Academy, a charter school, Gray said. The bus is operated by Aqua Limousine Ground Transportation, he said.