Egyptian officials investigating the massacre of worshippers at a mosque in Sinai say the attackers were carrying the flag of the Islamic State group.
At least 305 people died in the assault, which was launched during Friday prayers and has not yet been claimed by any group.
Egypt’s public prosecutor said there were up to 30 attackers at the scene.
President Abdul Fattah al-Sisi has vowed to respond with “the utmost force”.
The Egyptian military says it has already conducted air strikes on “terrorist” targets.