A senior security official near the crash site in Assiut said 44 of the dead were children, aged around four to eight.
Two women and a man, who was probably the bus driver, also died.
The state news agency said another 13 people were injured, while a medical source said as many as 28 were injured, 27 of them children.
There have been a string of accidents on Egypt's roads and railways, which have a poor safety record.
More top news
Ted Robbins is "doing well" and is expected to be "fit and healthy soon" after collapsing on-stage during Phoenix Nights Live, his wife said
Doctors in India have carried out what is believed to be the world's first double hand transplant to be performed on a non-white patient.
Prince George is not only heir to Britain's throne, but a future long distance runner too, if his uncle has anything to do with it.