A bomb blast killed two Egyptian police officers and wounded five others in an attack on an armoured vehicle in the Sinai Peninsula, the interior ministry said.
The vehicle was targeted near a school in the North Sinai provincial capital of El-Arish on Friday, the ministry said in a statement - the second violent incident in recent days.
Late on Thursday, at least three children were killed and seven people wounded in crossfire between Egyptian security forces and fighters in the region.
There was no immediate claim of responsibility but the region is a stronghold of the Islamic State of Iraq and
the Levant group.
Armed groups have regularly attacked security forces in the peninsula since the army ousted former president Mohamed Morsi in July 2013.
They say their attacks are in retaliation for a government crackdown on Morsi supporters that has left hundreds dead and thousands in prison.
The authorities say hundreds of policemen and soldiers have been killed in attacks, mainly in North Sinai, since 2013.