At least eight policemen have been killed in an attack on a checkpoint in the northern Sinai city of al-Arish.
The attack was launched with a car bomb, planted in a street cleaning car that the attackers had stolen a few days earlier, security sources said.
After the bomb exploded, attackers fired guns and rocket-propelled grenades at the checkpoint, they said.
There was no immediate claim of responsibility for the attack, which also wounded 13 people, including four civilians.
Police found the body of one of the attackers driving the vehicle that exploded.
An Islamist insurgency in the rugged, thinly populated Sinai Peninsula has gained pace since the military toppled President Mohamed Mursi of the Muslim Brotherhood, Egypt's oldest Islamist movement, in mid-2013 following mass protests against his rule.
The militant group staging the insurgency in Sinai pledged allegiance to Islamic State in 2014 and adopted the name Sinai Province.
It is blamed for the killing of hundreds of Egyptian soldiers and policemen since then.
In late November Islamic State claimed responsibility for an attack on a security checkpoint that killed 15 soldiers.
In its weekly online magazine Al-Nabaa released in November, Islamic State urged members to join other branches of the group active in areas like Sinai, Libya, Yemen and West Africa if unable to reach its self-declared "caliphate" in Iraq and Syria.