The attack took place near the provincial capital of El-Arish during Friday prayers, police officials said.
Witnesses said the explosive device was detonated next to the Al-Rawdah mosque in the center of the town of Bir al-Abd, according to Egyptian newspaper Al-Masry Al-Youm.
Dozens of people are thought to have been killed or injured after a massive suspected suicide attack on a Mosque in the Egyptian province of Sinai.
Egyptian defense officials said the attack began with explosions and then assailants began firing with machine guns into the mosque.
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Militants in the area have declared allegiance to Islamic State (ISIS) and carried out a number of attacks in recent years.
Ministry of Health spokesperson Khaled Mujahid said the militants set off a bomb during the attack, and that 75 casualties had been transferred to hospital.
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Egypt has been battling a jihadi insurgency in region since the Arab Spring and overthrow of President Mohamed Morsi in 2013.
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