Eight policemen were shot dead on Cairo's southern outskirts in an attack claimed Sunday by the Islamic State group, one of its deadliest in mainland Egypt.
The interior ministry said four assailants in a truck intercepted a van carrying the police officers in the district of Helwan, just south of Cairo, and sprayed them with automatic rifle fire.
It said those killed in the shooting overnight included a lieutenant and seven lower ranking policemen who had been on patrol in plain clothing.
In a statement circulated on social media, IS said "a squad of the soldiers of the caliphate" opened fire on the police van and then made off with their weapons.
It said the attack was carried out in retaliation for "women imprisoned" in Egyptian jails.
Jihadists have killed hundreds of policemen and soldiers in attacks, mostly in the Sinai Peninsula and also in and around Cairo, since the military toppled Islamist president Mohamed Morsi in 2013.
Militants had carried out a previous attack in Helwan, killing a policeman standing guard outside a museum in June 2015.
IS jihadists, who are based in the sparsely populated Sinai Peninsula bordering Israel and the Palestinian Gaza Strip, have repeatedly tried to make inroads into the capital, where police have had more success in quelling them than in Sinai.
They have claimed several attacks in Cairo, including the bombing of the Italian consulate in July 2015.
More recently militants have conducted hit-and-run attacks on policemen in Cairo and small scale bombings.
They often claim their attacks are in retaliation for a bloody police crackdown on Islamist supporters of Morsi, which has killed hundreds of protesters and imprisoned thousands.
They have also targeted foreigners.
- Retaliation -
In October, the Islamic State group claimed responsibility for bombing a Russian airliner carrying holidaymakers from a south Sinai resort, killing all 224 people on board.
The group said it smuggled explosives concealed in a soda can on to the plane at Sharm El-Sheikh, a popular Red Sea resort in south Sinai.
That attack prompted Russia to suspend all flights to Egypt, and has lost the country hundreds of millions of dollars in tourism revenues.
The bombing came two months after IS militants abducted a Croatian oil worker near Cairo and beheaded him.
Police later tracked down the top IS operative in Cairo, who was linked to the Croat's murder, and killed him in a shootout.
But efforts to crush the insurgency in Sinai have floundered despite a massive army campaign.
In March, Islamic State gunmen killed 15 policemen at a checkpoint near El-Arish, the provincial capital of North Sinai.
The Islamic State group declared a "caliphate" nearly two years ago in areas under its control in Iraq and Syria.
The Sinai branch pledged allegiance to IS in November 2014, and since then its attacks have grown more sophisticated.
The military says it has killed more than 1,000 militants, occasionally publishing pictures of their bodies.
The statements are difficult to verify, with reporters having little access to the north of the peninsula.
Hundreds of multi-national forces soldiers are based in Sinai to monitor a peace agreement between Israel and Egypt, and Washington has indicated it would cut its troops over the jihadist threat.
The Pentagon said last month it remained "fully committed" to the mission but wants to use drones to assume some of the riskier work.