Nine people were injured in a minor blast on Friday morning in northeast Cairo, Egypt's Interior Ministry said.
Eight policemen and a civilian were wounded by shrapnel after an improvised roadside bomb targeting a police patrol in the capital's Ain Shams district went off, a ministry statement said.
The wounded included a police captain.
Security forces are now combing the area, and the injured have been taken to a local hospital.
Bombings and shootings have become commonplace in the capital and other parts of the country since the 2013 ouster of Islamist president Mohamed Morsi.
The bloodiest attacks however have occurred in the border Sinai region, with hundreds of police and military troops killed.
On 30 January a series of coordinated militant attacks in North Sinai killed at least 30 were people, including a number of civilians.