CAIRO, Nov 28 (Aswat Masriya) - A homemade bomb went off Friday in Cairo's Abdel Moneim Riad Square in downtown, head of Cairo investigations Mohamed Qassem said.

An unknown person threw the bomb from 6 October bridge, Qassem added. He was arrested by security forces and is currently under investigation.

Six people were injured earlier after an improvised explosive device (IED) went off in the Nile Delta province of Sharkiya, a security source said.

Egypt's ultra-conservative Salafi Front, called on people to take to the streets holding Qurans to "impose the Islamic identity". The rallies were scheduled to take off from several mosques in Egypt after Friday prayers, according to their official Facebook page.

An army brigadier was killed and two others were injured earlier on Friday after unidentified assailants shot them at Gesr al-Suez area in Cairo, the armed forces said in a statement.

Security apparatuses across Egypt raised their state of alert in main cities and squares in anticipation of the protests.