UPDATE 2: Bus heading to Egyptian capital Cairo swerves into canal trying to avoid truck.
An Egyptian bus crowded with passengers, many of them students, veered off the road into a canal south of Cairo on Sunday, killing at least 55 passengers, officials and survivors said.
The accident happened on the main highway between the Nile Valley city of Minya and the capital Cairo when the bus driver swerved in a bid to avoid an oncoming truck.
All of the dead drowned before rescue teams could reach them, a hospital official told newswire AFP.
It was the deadliest road accident in Egypt since 1987, when 63 Egyptians were killed in a collision between a bus and a train.
"I was riding in the bus and the next thing I heard was screaming and crying," one of the survivors, Nehad Ayad, said.
She said she managed to escape through a window that was shattered when the bus overturned before it fell into the Ibrahimiya canal.
A ticket collector told police investigators that the bus, which was designed to carry a maximum of 50 passengers, had been overloaded with about 70 people on board, a police officer said.
"The driver was going too fast," said Mikhail Wahba Hena, a university student who survived the crash.
At least 20 ambulances rushed to the scene of the accident near the village of Dahrut, about 200km south of Cairo, an AFP correspondent reported.
They were joined by local residents offering their help.
Frogmen were sent into the canal to comb the waters for survivors.
A strong current made their work difficult, a rescue worker said, but in the end a winch pulled the battered bus out of the canal.
"Fifty-five bodies have been recovered," an official said, adding that 10 injured passengers had been taken to hospital.
Many university students and government workers were among the dead, the official said.
Police have detained both the truck driver and the bus driver for questioning, a police official told AFP.
Survivors who spoke to AFP blamed the bus driver for the accident, saying he had been speeding and lost control of the steering wheel when he tried to avoid the oncoming truck.
The governor of Minya, Ahmed Dia Al-Din, pledged 10,000 pounds ($1,800) for the family of each of the dead.
Poor road conditions and vehicle upkeep compounded by lax traffic regulations cause thousands of accidents in Egypt each year. A new highway code came into force in August with the aim of improving road safety.
Traffic accidents kill around 6,000 people and injure another 30,000 each year, according to transport ministry figures.
Last week, 15 Coptic students were killed when their bus overturned while travelling from Minya to the Mediterranean city of Alexandria.
Eight people, including six schoolgirls, were killed in September when a truck plunged into a river in the Nile Delta province of Sharqiya.