A bomb attack on a police vehicle killed six members of Egypt's security forces on Sunday, the latest in a wave of bombings and shootings targeting police and army troops.
Five others were injured when the roadside bomb went off near an armoured vehicle in the southern part of the North Sinai capital of Al-Arish, according to a military spokesperson.
Security forces were combing the area to search for the perpetrators, a military source told Al-Ahram Arabic news website.
Egypt has been rocked by a deadly Islamist insurrection, based in North Sinai, which has killed hundreds of police and military personnel since the ouster of president Mohamed Morsi in July of last year.
Late last week, three policemen were killed in a rocket-propelled grenade attack in Sinai, and 11 others were injured in a bomb attack on a religious festival in the Nile Delta city of Tanta.
The challenge to combat militant violence is compounded by the rise of Islamic State militants who have seized large territories of Syria and Iraq and declared an Islamic caliphate.
Egyptian officials are concerned the group has inspired or forged ties with militant groups in Egypt, including those based in the borderlands of the Sinai Peninsula.