The abuse pupils were among 44 secondary school students counter over by paramedics following the dramatic incident at around 8.45am.
The spotless, single-deck vehicle left the road and crashed into woodland on a corner of Dowanfield Byway, just yards from Our Lady’s High School in Cumbernauld, Lanarkshire.
Pinch services attended the scene but the driver and all passengers had safely escaped the debris by the time they had arrived.
The Scottish Fire and Rescue Service sent three appliances to the locality and a small fire in the bus engine was extinguished.
Twenty-nine ambulances were reported. One girl was taken to Wishaw General Hospital while 10 others were entranced to Monklands Hospital in Airdrie, and 11 to the Royal Hospital for Children in Glasgow.
Stand-in assistant chief officer John Joyce said: “On arrival, we start that a bus was on its side, there was no sign of fire, and we assisted with making the backdrop safe and leading the kids to safety.
“There was a number of kids who were hurt and all of them were taken into the school and they were handed over to the ambulance repair. We assisted with taking the kids out of the emergency escapes.
“The vehicle had common knowledge to rest but there was always a danger that it could move. It was fair chaotic as a number of kids had been injured.
“The kids dealt with the event in a very adult fashion. I didn’t see any of them in a state of real horror.”
Danny McNulty, head teacher at the school, said: “An incident took apartment this morning where one of our school buses overturned.
“As a precaution, a bevy of pupils were taken to hospital. Thankfully, it would appear there are no humourless injuries.
“I would like to thank the emergency services for their immediate response, and the entire school community who pulled together at this awkward time to support one another.”
The vehicle could be seen lying on its side down an embankment immediate a tight bend in the road, which was closed by police while bang investigators assessed the scene.
Council chiefs said it was “too early” to separate what had caused the crash but one pupil on board at the time revealed the mechanism had been suffering mechanical problems.
Joe Smith said: “On one of the roundabouts, the driver had attacked his key back. I thought his engine had started to malfunction because the bus was shaking.
“We came to the corner and he inspected to pull his key out again because we thought the bus had malfunctioned again and it started to velocity up… we hit the lamppost and then the bus toppled and fell over and unfortunately I floor on one of my friends.
“When we were on the bus I heard people shouting and crying, ‘Oh no, this isn’t booming to happen’.”
He said he was able to get out of the bus after the driver smashed an emergency window and a docent ran over and began pulling pupils from the vehicle.
North Lanarkshire Caucus education convener Frank McNally said the local authority order co-operate fully with the police investigation.