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
A band of thunderstorms
A 55-year-old man has died after being shot in front of shoppers in a packed supermarket car park in broad daylight.
The suspect, 35-year-old Willie Corey Godbolt, has been arrested and was being treated for a gunshot wound in hospital.