Egyptian presidency announced Wednesday a three-day period of mourning for the "martyrs of the nation", Al-Ahram Arabic website reported.
The stated martyrs include the 11 soldiers who died in North Sinai when a suicide bomber drove into their convoy on Wednesday, the 26 people who died on Monday in Giza when a train ploughed into a truck and a minibus at a railway crossing, and a senior officer in Egypt's National Security Apparatus, Mohamed Mabrouk, who was assassinated on Sunday.
Egypt's interim cabinet denied that a state of emergency would be reinstalled in the country following the Wednesday bomb attack, but said that an anti-terrorism law, drafted by the justice ministry, is currently being revised.
Meanwhile, in recorded and later televised comments, delivered upon the arrival on Wednesday evening of the slain soldiers' caskets at Almaza military air-base in Cairo, El-Sisi said that the attack would only increase the [government's] determination to fight back against those who use weapons against the military, the police and the state.
"People should know we are all ready to die in order for Egypt to stay alive," he said.
General El-Sisi was shown on state TV comforting the fallen soldiers' families, accompanied by Egypt's army chief of staff Lieutenant General Sedki Sobhi and Minister of Interior Mohamed Ibrahim.
"We do not fear, because we know if we fall while defending our country we will be martyrs; we will stand like martyrs in front of God," said El-Sisi.
The restive peninsula has seen a surge in attacks blamed on Islamic militants that targeted security in almost daily assaults since the ouster of Mohamed Morsi. Attacks on security and army targets in the Sinai region have killed tens of personnel since July.
Wednesday's attack is the bloodiest since mid-August when gunmen killed 25 police conscripts in an ambush on a security convoy in Rafah.
"Everyone who used weapons against the military and the police is a terrorist who want to crush his own people. We are there to fight this and be killed for this aim," El-Sisi said.
Dozens of militants have been killed since the army began a campaign to flush out "terrorists" and seize or destroy arms caches in the Sinai region.
"God only knows the pain in our souls," El-Sisi said in ending his speech.