Under floodlights, rescue teams combed wrecked carriages all night for casualties, also using torches on their mobile phones.
The toll from Friday's accident when two trains hurtled into each other near Alexandria has risen to 40 dead and 123 wounded, said health ministry spokesman Khaled Moujahed, as local media said the number of fatalities was likely to rise.
The crash on the route to Cairo, derailed the engine of one train and two cars of the other, the Egyptian Railway Authority said.
A railroad switching error was the most likely cause of the collision, according to a security source.
Workers used cranes to lift four knotted sheet-metal carriages blocking the normally busy Cairo-Alexandria line.
Transport ministry officials, quoted on state television, have said the crash in farmland on the outskirts of Alexandria was probably caused by a malfunction in one train that brought it to a halt.
The other train then crashed into it.
One train had been heading to Alexandria from Cairo and the other from Port Said, east along the coast.
Egyptian President: 'hold accountable'
President Abdel Fattah al-Sisi has sent his condolences to the victims' families and ordered a probe to "hold accountable" those responsible for the disaster.
It was the deadliest train accident in the North African country since a train ploughed into a bus carrying schoolchildren in November 2012, killing 47 people.
That accident jolted the government which ordered an investigation and sacked the transport minister and the head of the railway authority.
The accident was blamed on a train signal operator who fell asleep on the job.
The probe, however, did not prevent further accidents. Just months later, a train carrying military conscripts derailed, killing 17 people.
Around a year later, a collision between a train and a bus killed 27 people south of the capital.
They had been returning from a wedding when the train ploughed into their bus and a truck at a railway crossing.
Chronic transport problems
Egyptians have long complained that the government has failed to deal with chronic transport problems, with roads as poorly maintained as railway lines.
There have been many other fatal crashes on the busy rail network.
In July 2008, at least 44 people died near Marsa Matruh in northwestern Egypt when a runaway truck hurtled into a bus, a lorry and several cars waiting at a level crossing, shunting the vehicles into the path of a train.
At least 58 Egyptians were killed and 144 injured in August 2006 in a collision between two trains travelling on the same track.
In the wake of that crash, a court sentenced 14 railway employees to one year in prison for neglect.
The deadliest accident on Egypt's railways dates back to 2002 when 373 people died when a fire ripped through a crowded train south of the capital.