Militants killed eight Egyptian policemen on Wednesday at a checkpoint in the Sinai Peninsula, centre of a long-running jihadist insurgency, the interior ministry said.
"Terrorist elements targeted a checkpoint west of El-Arish early this morning... The exchange of fire killed fire terrorist elements and eight police were martyred," a ministry statement said.
Some militants escaped and security forces are following "their movements", the ministry added.
A security source said reinforcements had been dispatched to the checkpoint near El-Arish, capital of North Sinai province.
"The checkpoint is currently surrounded by the army and police," he said.
A medical source said three members of the Central Security Force, a paramilitary force under the control of the interior ministry, were also wounded in the attack and taken to El-Arish public hospital.
Egyptian state television said there were fears the death toll could rise as there were reports of attacks on multiple checkpoints.
The attack came at the start of the Muslim holiday of Eid al-Fitr, marking the end of the fasting month of Ramadan.
No group has claimed responsibility so far.
Egypt has for years been battling insurgents in the North Sinai affiliated with the Islamic State group.
Hundreds of police officers and soldiers have been killed in militant attacks which intensified after the army's ouster of Islamist president Mohamed Morsi in 2013.
In February 2018, the army launched a nationwide offensive against the militants focused mainly on the North Sinai.
According to official figures, around 650 militants have been killed since the start of the operation, while the army has lost some 50 soldiers.
No independent statistics are available and the region is largely cut off to journalists making verification of casualty figures extremely difficult.