Fifty people, mostly children, were killed when a train crashed into a school bus as it crossed rail tracks in the Egyptian city of Manfalut, south of Cairo on Saturday.
Watch this report from Damon Green.
State media and security officials in Assiut, near the scene of the incident, said that all but two of the dead were children, aged around four to eight.
One woman and a man, probably the bus driver, also died, said officials.
The bus was broken in half by the force of the crash, images from an Egyptian newspaper showed.
Transport Minister Mohamed Rashad submitted his resignation after the accident, an offer which President Mohamed Mursi was considering, state media reported.
Egypt's roads and railways have a poor safety record and Egyptians have long complained successive governments have failed to enforce even basic safeguards, leading to a string of deadly crashes.
State television said that as well as the 50 dead, 18 people were injured. A medical source said as many as 28 were injured, 27 of them children.
Assiut Governor Yahya Keshk also said the railway crossing was open when the train hit the bus: "The crossing worker was asleep. He has been detained," he told state television.
"I saw the train collide with the bus and push it about 1 km (half a mile) along the track," said Ahmed Youssef, a driver.
Officials said the level of destruction and mutilation made it difficult to count and identify the bodies.