A bomb explosion has killed six police officers near the border town of Rafah in Egypt's Sinai Peninsula, in an attack that bore the hallmarks of a local al-Qaeda-inspired group, Egyptian security officials say.
Security officials said the bomb was hidden deep under the asphalt of a highway, in an area called Wadi Halfa, where a joint police and army force was passing early in the morning on Tuesday.
The official said the blast also injured two police officers, shredding the armoured vehicle and tearing the bodies of the police fatalities.
The force was assigned to detect explosives but it was unclear if they were searching for them at the time of the attack.
No further details were immediately available. The official spoke on condition of anonymity because he is not authorised to brief the media.
Armed rebel groups have escalated attacks over the past year against police and army personnel in retaliation for the military-led overthrow of President Mohamed Morsi after mass demonstrations against him.
Suicide bombings, assassinations and road side bombs have claimed the lives of dozens of policemen and army officers.
Recently, an armed group beheaded men they accused of spying on them for Israeli intelligence.
While authorities blame Morsi's Muslim Brotherhood group over the violence, another al-Qaeda inspired group known as Ansar Beit al-Maqdis has claimed responsibility for most of the major attacks.
The group said it is avenging the authorities' extensive crackdown on Morsi's supporters who have been staging near daily protests demanding his reinstatement. The clampdown has killed hundreds and jailed thousands.
Violence is more intense in the Sinai Peninsula, home to Ansar Beit al-Maqdis and other rebel groups.
For years, the northern region bordering Gaza and Israel has been a stronghold for armed rebels and base for weapons and smuggling to and from Gaza.
Since Morsi's overthrow, Egyptian military and police have launched a wide offensive against the rebel group, but counterattacks continue.
Tuesday's bombing was identical to a September 2 explosion that killed 11 police officers in the same area, also with an underground roadside bomb detonated by remote.
Ansar Beit al-Maqdis claimed responsibility for the attack days later, posting a video showing its preparation and execution as armed men shouted "God is great."
On Monday, the military said its troops had killed 56 rebels and seized large amount of explosives over the period between August 31 and mid-September.