Al-Jazeera colleagues Mohamed Fahmy and Baher Mohamed were among the pardoned group.
The three -- Canadian national Mohammed Fahmy, Australian journalist Peter Greste and Egyptian producer Baher Mohammed -- were sentenced after a lengthy retrial.
The Egyptian government has ordered military special forces to assist the police in securing vital state facilities across the country.
The gunmen in four off-road vehicles opened fire on the people who tried to exit the mosque after the explosion.
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.
Two powerful blasts triggered by Islamic State in two churches packed with worshippers celebrating Palm Sunday in Egypt's Tanta and Alexandria cities.
Ousted Egyptian President Hosni Mubarak was on Saturday acquitted by a court which found him not guilty in the killing of hundreds of protesters during the 2011 revolution that toppled his nearly three decades-long rule, overturning an earlier ruling.
Over the last four days, Prime Minister Narendra Modi greeted the heads of over 50 African nations, some of whom have extremely unsavoury reputations. Meet the 10 most controversial leaders who visited Delhi this week.
The rankings were prepared after examining the volume of terrorist and rebel alerts, messaging traffic, videos, photos, incidents and the number of killed and injured in a country over the past 30 days.
'Did Trump hint at US military intervention in Qatar?' asks Ambassador M K Bhadrakumar.
Why is Xi Jinping visiting Saudi Arabia, Egypt and China this week? Former RA&W officer Jayadeva Ranade explains the significance of China's outreach to the Middle East.