Six policemen were killed and three wounded on Friday when a roadside bomb exploded near a security checkpoint in Cairo, the interior ministry said.
The attack, close to a government building in a middle class neighborhood of Cairo, was the latest in a series of security incidents in Egypt often claimed by terrorist groups.
There was no immediate claim of responsibility for the blast in which four civilians were also hurt, security sources said.
The policemen were either in or near their car when the device went off, Reuters reported.
The ministry said a security cordon had been thrown around the scene of the attack near a mosque in the Giza District of the Egyptian capital.
Eyewitness Ahmed Al-Deeb described a scene of carnage, with dead and dying policemen lying next to wrecked cars. One of the policemen had blast fragments in his chest and two more had lost legs, he told Reuters Television.
An Egyptian general was killed by militants on November 4 near his home in North Sinai in an attack claimed by the self-styled Islamic State terrorist group. He was the second military officer of his rank to be shot dead in as many weeks.
Hundreds of soldiers and police have been killed in an insurgency led by IS in the Sinai Peninsula.
