Censor.NET reports citing Reuters.
The bomb exploded as the police arrived in their vehicles in front of a building where suspected militants were hiding, the sources said. 13 people were wounded.
The Interior Ministry issued a statement saying the bomb had been planted by Muslim Brotherhood militants and went off when security forces tried to raid the building.
Islamist militants have stepped up attacks on Egyptian soldiers and police since the army toppled president Mohammed Mursi of the Muslim Brotherhood in 2013 after mass protests against his rule. Civilians have also been killed.