Anger, sectarian tensions, and fear of continued violence all seem palpable in city streets across Egypt on Friday as "day of rage" marches were called against the military-backed government just two days after a massacre that left over 600 people dead in Cairo.

Reports indicate tightened security nationwide by the army and security forces, but backers of ousted president Mohamed Morsi vowed to march regardless of threats that "live ammunition" would be used by security forces against protesters.

As Friday prayers let out and the marches began, witnesses and journalists near a main bridge in Cairo report the sound of repeated gunfire already underway.

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Al-Jazeera reports:

the military forces closed off entrances and exits and roads leading to Cairo's Tahrir Square with armoured personnel carriers and barbed wire.

The Anwar Sadat metro station in Tahrir Square was shut down as a precautionary measure.

Security forces also closed off all streets leading to Rabaa al-Adawiya mosque.

Armoured personnel carriers had been deployed in several places in central Cairo.

Egyptian state TV reported that the military had deployed troops to guard what it described as vital installations.

Army commanders gave warning that troops would fire at anyone who attacked government buildings.

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