Three civilians were killed on Wednesday in a roadside bomb in North Sinai, state news agency MENA reported.
A bomb planted on the side of a highway south of the provincial capital of Al-Arish caused the deaths.
Extremists have been waging an insurgency in the northern part of the Sinai Peninsula that has mainly targeted policeman and soldiers in bombings and ambushes.
The military have spearheaded an extensive campaign to crush militants in the region that borders Israel and the Palestinian Gaza Strip, which has killed hundreds of militants.
The army said it had killed 88 extremists in the third phase of its 'Right of the Martyr' campaign in May, and that another 22 were killed in a multi-day operation early last month.
On Sunday, a gunman shot dead a police officer in North Sinai in an attack claimed by the Egyptian affiliate of the Islamic State militant group.