The Egyptian Government has declared three days of mourning following the attack on al-Rawdah mosque, which has injured at least 80 people.
The mosque is in the volatile northern Sinai Peninsula, around 25 miles from the provincial capital of el-Arish, which has been regularly targeted by IS militants in recent years.
State television reports that the attack – which came as worshippers took part in weekly Friday prayers – has likely been carried out by IS and President Abdel Fattah al Sisi has called an emergency security meeting.
Officials said the militants arrived at the mosque in four off-road vehicles before detonating a bomb and opening fire, with ambulances then seen taking casualties to local hospitals.
IS militants have killed hundreds of police and soldiers in the region since fighting intensified over the last three years, although they have mostly targeted Egypt’s security forces.
They have also struck against Christian churches and pilgrims in the country.