Montgomeryshire MP Craig Williams, raised the horrifying incident in the House of Commons during Prime Minister's Questions.
The crash took place in Llanfair Caereinion on Monday afternoon – with five children hit by a bus.
Four children were taken to hospital – three by air ambulance, while a fifth child was discharged at the scene.
The driver of the bus was also taken to hospital.
There has been no official confirmation of the condition of those injured in the incident, but Mr Williams told the House of Commons that "everyone is in a stable condition".
The MP, who has two children who attend Llanfair Caereinion Primary School, spoke to praise the teaching staff at both Llanfair primary and high schools, as well as the police and ambulance staff who responded to the incident.
He said: "On Monday at 3.25pm a school bus crashed into a group of school children in Llanfair Caereinion. Three children were airlifted to hospital with another child and a bus driver taken by ambulance and a fifth child discharged at the scene.
"Everyone is in a stable condition. Clearly this is a tragic accident that will stay with the community for some time.
"Will the Prime Minister join me and I am sure the whole house to send our love and prayers to those in hospital?
"Will he also praise the teaching staff of both the primary and high schools, the Wales Air Ambulance, and Dyfed Powys Police for their heroic response and their continuing response to the community?"
Replying, Boris Johnson offered his own thanks to those who had come to aid those injured in the incident.
He said: "I thank my honourable friend for raising this very sad incident so I am sure the whole house's thoughts will be with those who have been affected and I want to join him in particular in paying tribute to the emergency services, but also of course the teachers and staff of the schools who did so much to help."