A masked Egyptian masked policeman watches Tahrir Square in Cairo, Egypt.

:: ISIS militants in Egypt’s restive northern part of the Sinai Peninsula ambushed local tribesmen who were securing an area in the region, killing 10, security officials said.

The men were from the Tarabin tribe and were manning a checkpoint near a militant-stronghold south of the border town of Rafah when the militants approached them in a vehicle and opened fire, said the officials, speaking on condition of anonymity because they were not authorized to talk to reporters.

Local residents who witnessed the attack told The Associated Press that the militants were using a security vehicle they had apparently captured in fighting from security forces. The eyewitnesses also spoke on condition of anonymity, fearing retribution.

No militant group immediately claimed responsibility for the attack.

Sinai’s powerful tribes have stayed on the sidelines of the battle between Egyptian authorities and a growing insurgency led by the ISIS militant group that has been raging in North Sinai in recent years.

However, an open conflict between the tribesmen and the militants emerged in recent weeks.

In late April, an ISIS suicide bomber killed four tribesmen standing watch in Rafah. The tribes retaliated by killing eight suspected ISIS fighters in a battle in the town earlier this month.

Moussa al-Delh, a powerful member of the Tarabin tribe announced earlier this month in a statement on his Facebook page that the tribe is in war with militants under the leadership of the state, inviting other Sinai tribes to join the fight.