Protesters who were in Tahrir Square to commemorate the second anniversary of the deadly Mohamed Mahmoud Street clashes fought with supporters of army chief General Abdel-Fattah El-Sisi.
Both groups threw rocks at each other as the Mohamed Mahmoud protesters tried to prevent the pro-army demonstrators from entering Tahrir.
Protesters hold the army and police responsible for the death of 47 protesters in the 2011 clashes.
Video by Simon Hanna.