CAIRO: Egyptian Central Security Forces today fired tear gas at demonstrators protesting in Tahrir Square this afternoon during their extension of the “Sole Demand” Friday. Protestors retaliated with rock-throwing. The recent clashes in Tahrir has thus far led to 27 injuries including one CSF officer, reported the Egyptian Health Ministry. “The injured have been transferred to the al-Mounira Hospital and there are no serious cases,” said Assistant Minister of Health Adel el-Addawy. Roughly 1,500 demonstrators organized an indefinite sit-in in Tahrir Sqaure after yesterday's demonstration, despite the calls from some political and national powers to end the protest. The demonstrators are demanding the transfer of power to a civil authority, the rejection of the constitutional principles document presented by Deputy Egyptian Prime Minister Ali el-Selmy as well as other January 25 Revolution demands. Several public committees refused to reopen the square and used barricades to halt the flow of traffic. Military police interfered to disperse the demonstrators early this morning, removing tents and physically moving some demonstrators. Two were injured in the siege. The military also attempted to prevent protestors from taking photographs and shooting video. The shop owners in the Tahrir area closed down for the day fearing escalating insecurity. Security forces arrested four protestors who allegedly assaulted members of the military during the evacuation of the Square. The CSF also sent in four armored vehicles to secure the entrances of the Square. Some demonstrators attempted to return to the Square after its evacuation, sparking new, more vigorous, clashes between the military, the CSF and protestors. Seven demonstrators have thus far been detained. The demonstrators most recently set ablaze a CSF truck amidst heavy tear gas.