Four children were hurt after a hedgetrimmer cut open a double-decker bus like a tin can.
Paramedics were called to the freak accident in Essex at 8.22am today.
Trevor Redburn, assistant general manager for the East of England Ambulance Service in North Essex, said: "We arrived within five minutes and it was quite a scary-looking scene.
"We counted 45 children who were all shocked and confused."
The four who were hurt were described as having "slight injuries".
The vehicle responsible had been trimming branches along Alresford Road in Wyvenhoe.
A replacement bus service was organised and parents arrived to take the injured children to hospital.
Mr Redburn added: "I want to commend our team for the work they did in quickly identifying the injuries and providing everyone with a full assessment."
