Cairo - Four children and a woman were killed on Friday when a mortar round crashed into their home in North Sinai, where the Egyptian army is battling jihadists, officials said.
Security and medical sources said the woman and the children, aged between 6 and 16, died in Sheikh Zuweid, near North Sinai's main town of El-Arish.
It was unclear which side fired the mortar round, a type used by both the army and militants.
Five civilians were killed on Wednesday in a similar incident in the same area.
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North Sinai is a bastion of the "Sinai Province" jihadist group.
Formerly known as Ansar Beit al-Maqdis, it changed its name when it pledged allegiance to the Islamic State group in November.
On July 1, the group carried out a series of attacks on security forces in Sheikh Zuweid that the military said killed 21 soldiers.
The jihadists say their attacks are in response to a crackdown launched by the authorities after Islamist president Mohamed Morsi's ouster, which has seen at least 1 400 people killed and thousands more jailed.