Militants on Wednesday killed eight Egyptian policemen at a checkpoint in the Sinai Peninsula in an attack claimed by ISIS.
Authorities said militants killed the officers at a checkpoint west of El Arish, capital of the North Sinai region, as Muslims celebrated Eid Al Fitr.
Five terrorists also died in the attack and security forces were pursuing others who escaped, the Egyptian Interior Ministry said.
The north-eastern region is the centre of a years-long insurgency by militants, some linked to ISIS, who have regularly attacked security forces.
Amaq, the propaganda wing of ISIS, said its fighters had launched "two simultaneous attacks on two police checkpoints" in El Arish.
It said its fighters killed several officers and destroyed tanks before leaving the area.
ISIS said one checkpoint was Al Sabil, which a security source confirmed had been targeted.
The terrorist group said the attack was aimed at undermining Egyptian authorities' assertions that the city was safe.
A security source said two of the militants hijacked two tanks belonging to the Central Security Forces.
But a fighter jet destroyed one and security forces killed the other militant in a shootout, the source said, showing photos of the charred tanks.
He said reinforcements had been sent to the checkpoint near El Arish.
"The checkpoint is surrounded by the army and police," he said.
Three members of the Central Security Forces were wounded in the attack and taken to El Arish public hospital.
Egyptian state television said there were fears that the death toll could rise, amid reports of attacks on other checkpoints.
Egyptian social media users, including Liverpool footballer Mohamed Salah, paid tribute to the police officers killed as Muslims marked Eid.
"Heartfelt prayers to those martyrs of El Arish checkpoint. Sending condolences to all the families of the martyrs killed today," Salah wrote on Twitter.
Egypt has for years been battling North Sinai insurgents affiliated with ISIS.
Hundreds of police officers and soldiers have been killed in militant attacks, which surged after the army removed president Mohammed Morsi, of the Muslim Brotherhood, in 2013.
Police raids in May killed 16 militants in North Sinai, the Interior Ministry said.
It said last month that it had intelligence that militants were planning attacks on "important and vital facilities", and prominent figures in El Arish.