It is believed that a bomb was detonated inside the crowded Sufi mosque, before shots were fired on worships fleeing for their lives.
305 people have been killed in the attack, with another 128 wounded, in what officials have said is one of the worst terrorist attacks in recent history.
Egypt is a danger zone with Islamic State (ISIS) insurgents terrorising areas of the country, but the latest incident has shocked the nation not just because of the amount of deaths but also the choice of target.
Attacks on mosques are rare in Egypt, with ISIS normally avoiding Muslim places of worship. In this case most of the victims were Sufi Muslims.
President Donald Trump was one of a number of world leaders who condemned the mosque attack and wrote:
"Will be calling the President of Egypt in a short while to discuss the tragic terrorist attack, with so much loss of life. We have to get TOUGHER AND SMARTER than ever before, and we will. Need the WALL, need the BAN! God bless the people of Egypt."
Egypt’s president and air force have vowed to respond with the “utmost force” against the Muslim terrorists, and have already conducted air strikes against the suspects.