The source of the explosion was not immediately known and an investigation has been ordered, the official added.
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 reportedly killed in militant attacks since then.