Officials suspect Islamic State to be responsible for the attack.
Army spokesperson Tamer el-Refai said in a statement that the air forces launched retaliatory attacks on terror hideouts in the surrounding area of North Sinai, killing militants and destroying vehicles used in the deadly attack.
The gunmen in four off-road vehicles opened fire on the people who tried to exit the mosque after the explosion.
The incident took place after a train coming from Cairo, the capital of Egypt, collided with another train coming from Port Said in Khorshid area.
The Egyptian government has ordered military special forces to assist the police in securing vital state facilities across the country.
Two powerful blasts triggered by Islamic State in two churches packed with worshippers celebrating Palm Sunday in Egypt's Tanta and Alexandria cities.
Mubarak was sentenced to life in prison in 2012 for taking part in killing over 200 protesters during the 18-day revolt which began on January 25, 2011, but a retrial was ordered on appeal.
The explosion took place at St Mark's Cathedral, main Coptic Christian cathedral, in Abbassyia district of central Cairo around 10:00 am when the prayers were on, according to a statement by the ministry of health.
Egypt's toppled Islamist President Mohamed Morsi was on Saturday sentenced to life imprisonment by a court for passing state secrets to Qatar.
The vessel 'John Lethbridge' that is affiliated to the company Deep Ocean Search found the cockpit voice recorder of the Airbus A320, according to a statement by the Egyptian committee that investigated the crash of plane.
The navy has also found some of the passengers' belongings and was sweeping the area in search of the plane's black box, the military said.
The plane was last detected in the skies over Greece, about 40 minutes from Athens, according to Sky News Arabia.
Three masked men on motorcycles threw the firebombs into the club in the Agouza district early Friday morning and fled.
Islamic State militants detonated a powerful car bomb outside the Italian consulate in Cairo, killing a civilian and injuring 10 people, the first assault on a foreign mission in Egypt since militants launched a campaign against security forces after Mohammed Morsi's ouster in 2013.
The Egypt-born actor's agent Steve Kenis said, "He suffered a heart attack in a hospital in Cairo."
The coordinated assaults in the morning set off fierce fighting between the army and the militants that is currently ongoing, with soldiers and police chasing the attackers using ground and air force, security sources said.
The bomber was killed outside the popular Karnak temple which is the second largest ancient religious site in the world.
An Egyptian court on Tuesday upheld the death sentences against 11 people for their involvement in the country's worst-ever soccer violence that killed 74 fans after a top-league game in the coastal Port Said city.
Saturday's capital punishment ruling against Morsi makes him the first president in Egypt's history to face the possibility of death by hanging.
Ousted Egyptian President Hosni Mubarak and his two sons were on Saturday sentenced to three years in prison.