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
Staying very chilly
Britain must deliver "more progress" on the Brexit divorce bill and the Irish border by the beginning of December, Donald Tusk has said.
A helicopter and an aircraft have been involved in a mid-air collision over Buckinghamshire.