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
Some students argued that the centuries-old tradition of wearing gowns, suits and mortarboards to exams was 'archaic' and looked elitist.
Clear spells in the north overnight where it's actually cold enough in the north for a touch of ground frost. Further south cloudier.
Grange Hill actor Terry Sue-Patt, who played Benny Green in the long-running school-based drama, has been found dead at his home in London.