Central Security Forces (CSF) broke the two-hour-old truce that was reached between protesters and the police in mid-afternoon.
A video circulating on the internet shows how protesters chanting "Peaceful, peaceful, peaceful" as they stood in Mohamed Mahmoud Street were taken unawares and came under a sudden attack from security personnel.
Ahram Online reporters on the scene say that CSF troops started attacking protesters who were gathered peacefully in Mohamed Mahmoud Street near the entrance of Tahrir Square. CSF soldiers also attacked protesters in Falaki Square from the direction of Mohamed Mahmoud Street.
Mohamed Mahmoud Street, directly south of Tahrir, has been the scene of constant clashes and tear gas attacks by the police forces over the past five days.
The brief cessation of hostilities came as a result of a truce brokered by a number of independant figures and the Ministry of Interior.
The street is littered with debris from the battles and the smell of tear gas still permeates the air, stinging the eyes of protesters who walk back and forth chanting "We will not leave, he [SCAF] should leave" and "Muslims and Christians are one hand."
"The truce is only temporary," a protester had, propheticaly, told Ahram Online earlier in the afternoon as the people on the street made their way back to Tahrir Square.
"It is only to give a chance to the general procecution [who went to investigate the clashes] to finish their mission. However we don't trust the police. They might attack again at any time."
Many protesters went back to the square to rest. Meanwhile animal rights activists have been busy rescuing pets stranded in a petshop on the street.
Indeed, CSF armoured vehicles remained in streets leading to Tahrir Square during the two hours of relative calm.