A roadside bomb blast wounded 15 policemen on Thursday as they travelled in a bus in northern Sinai where militants have launched deadly attacks against security forces.
The military is fighting an Islamist insurgency in North Sinai, which grew since the 2013 ouster of president Mohamed Morsi by then army chief and now President Abdel Fattah al-Sisi.
Thursday's attack on the outskirts of North Sinai's provincial capital of El-Arish targeted a bus carrying policemen who were on leave, medics and security officials said.
The blast was detonated by remote control, security officials said.
North Sinai is a bastion of a jihadist group calling itself "Sinai Province". 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 the town of Sheikh Zuweid in the Sinai. The military said 21 soldiers were killed in those attacks, after several media outlets reported higher tolls from security officials.
The jihadists say their attacks are in response to a crackdown launched by the authorities after Morsi's ouster which has seen at least 1,400 people killed and thousands more jailed.