Cairo's Tahrir Square on Friday witnessed a huge explosion after unknown assailants had thrown a burning gas cylinder inside al-Hawatiya School playground behind the American University in Cairo building.
Firefighters are exerting all efforts to put out the fire.
Clashes between the protesters and security forces stationed behind the concrete wall in Sheikh Rihan's Street intensified.
Several protesters were injured as well a policeman, an officer, and five conscripts.
Egyptian protesters in several governorates have been demonstrating since Friday morning to commemorate the January 25 revolution's second anniversary and demand completing the revolution's objectives.