At least 25 people were killed on Wednesday when a 12-storey building collapsed in the Egyptian coastal city of Alexandria, the health ministry said.
Another 12 people were injured, deputy health minister Mohammed al-Sharkawi told AFP.
More people were trapped under the rubble and were calling out to rescue teams for help, an interior ministry official said.
Emergency services rescued 10 people after the building housing 24 families in the Maamura district of Alexandria collapsed in the early hours, a security official said earlier.
Another two people were killed when a three-storey building collapsed in the Nile Delta province of Daqahliya, a security official told AFP.
"A mother and her child were killed and eight others injured when the building collapsed," the official said, adding that an estimated 10 people were still under the rubble.
Egypt has seen a number of construction disasters over the years, many of them blamed on planning violations or bad maintenance.
In a third incident on Wednesday, four people were killed when a train hit a taxi at a level crossing west of Cairo, state television reported.
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According to media reports, that would make it the sixth deadly train accident since Mohammad Morsi was sworn in as Egypt's first Islamist president in June.
On Tuesday, 19 people died and more than 100 were injured when a train carrying military conscripts derailed southwest of Cairo.
The latest incidents will pile pressure on Morsi's government, which has been criticised for failing to address Egypt's chronic problems.
Transport Minister Hatem Abdel Latid told journalists on Wednesday that the "process of developing the railway sector will need at least 15 billion Egyptian pounds ($2.3 billion)."
He said a meeting with governors will be held on Thursday to develop 28 crossings across the country, but stressed that "financing them will be at the cost of the local authorities."
The railway network's poor safety record stems largely from lack of maintenance and decades of poor management.
In Egypt's deadliest railway tragedy, the bodies of more than 360 passengers were recovered from a train after a fire in 2002.
Egyptians have long complained that the government has failed to deal with the country's transport problems, with roads as poorly maintained as railway lines.