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
Cancer surgeon accused of conducting series of 'completely unnecessary' operations denies giving cancer-phobic GP an unneeded mastectomy.
Health workers are set to be given a 1% pay rise, the Government has announced.
Facebook app rolls out new Snapchat-like camera features allowing users to create and share 'stories' and add filters and masks to images.