Two policemen were injured when unknown armed assailants targeted a patrol car north of Cairo early Thursday, state news agency MENA reported.

Masked gunmen opened fire intensely at a police vehicle combing the Ring Road, near Shubra Al-Keima in Nile Delta province of Qalyoubia.

On Wednesday, six army officers were killed in a twin car bombing by suspected Islamist militants targeting a military intelligence headquarters and a nearby army checkpoint in the restive Sinai Peninsula near Rafah, bordering the Palestinian Gaza Strip.  Ten soldiers and seven civilians were also wounded in the attack.

Egypt has seen a militant insurgency in Sinai surge after the army overthrew of Islamist president Mohamed Morsi 3 July, heightening fears that militant violence could spill over elsewhere in the country.

Last week, a suicide car bombing targeted the interior minister's convoy near his home in Nasr City, Cairo. Three, including the bomber, were killed and more than 20 wounded in the attack. The Sinai-based militant group, Ansar Bayt Al-Maqdis, later claimed responsibility for the assassination attempt, pledging more attacks.

The Egyptian military launched what it described as its largest assault on Islamist militants in North Sinai this week, targeting militant hideouts and weapons depots in a bid to "purge the region of terrorism."

At least nine militants were killed and nine others arrested in the operation.