Three people were killed and nine others injured as a huge explosion rocked Egypt's Al-Haram district in Giza, officials said.
The reason of the explosion is being investigated and a security team has been rushed to the spot.
Three of the injured are in critical condition.
Militants have launched a number of violent attacks in parts of the country since the January 2011 revolution that toppled the ex-president Hosni Mubarak.
The attacks targeting police and military increased after the ouster of Islamist ex-president Mohamed Morsi in 2013 by military following massive protests against his rule.
Over 600 security personnel have been reported killed since then.
