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 suspect has been apprehended after the shooting which is believed to have taken place as students made their way to morning classes.
A new national security communications unit to counter fake news and disinformation by foreign states is to be set up by the Government.
The actress told ITV News that government proposals would result in the deaths of more vulnerable women.