An Egyptian riot police officer fires tear gas during clashes with protesters near Tahrir square in Cairo, on November 22, 2011. #

An Egyptian protester holds a spent canister during clashes with Egyptian riot police in Cairo, on November 21, 2011. #

Protesters run for cover during clashes with the Egyptian riot police near Tahrir square in Cairo, on November 22, 2011. #

An Egyptian protester throws a rock during clashes with riot police along a road near Tahrir Square, in Cairo, on November 23, 2011. #

An Egyptian protester wearing a gas mask waves a national flag in Tahrir Square, the focal point of the recent Egyptian uprising in Cairo, on November 21, 2011. #

An injured Egyptian protester walks in Tahrir square in Cairo, on November 23, 2011 on the fifth day of clashes with security forces. #

Protesters clash with riot police along a road near Tahrir Square, in Cairo, on November 22, 2011. #

Protesters in Tahrir Square attend a funeral of a protester who died in clashes with riot police, in Cairo, on November 22, 2011. #

A boy with a face mask stands with his father in Tahrir square as clashes take place nearby with Egyptian riot police, in Cairo, on November 23, 2011. #

Protesters protect themselves against tear gas during clashes with riot police in a side street near Tahrir Square, on November 22, 2011. #

A protester wearing a protective mask takes cover from tear gas during clashes with riot police along a road near Tahrir Square, in Cairo, on November 22, 2011. #

An Egyptian protester prepares a Molotov cocktails during clashes with riot police near Tahrir Square, in Cairo, on November 23, 2011. #

An Egyptian protester carries various items through a street during clashes with riot police near Tahrir Square, on November 23, 2011. #

An Egyptian protester protects his face and head from tear gas during clashes with riot police in Cairo, on November 23, 2011. #

An Egyptian youth wearing a gas mask aims a slingshot during clashes in Cairo, on November 22, 2011. #

Egyptian riot police stand behind their shields as they clash with protesters near Tahrir Square, in Cairo, on November 23, 2011. #

A protester gestures toward riot police as tear gas is thrown his way during clashes in Cairo, on November 22, 2011. #

A youth takes cover during clashes with riot police on a road near Tahrir Square in Cairo, on November 23, 2011. #

A riot policeman fires a shotgun at protesters during clashes on a side street near Tahrir Square in Cairo, on November 23, 2011. #

Protesters run from huge clouds of tear gas fired by riot police during clashes near Tahrir Square in Cairo, on November 22, 2011. #

Protesters move away from tear gas fired by Egyptian riot police, not seen, during clashes near Tahrir Square in Cairo, on November 21, 2011. #

An Egyptian protester holds ammunition casings during clashes with Egyptian riot police in Cairo, on November 21, 2011. #

A protester runs with a smoking tear gas canister, to throw it back toward riot police during clashes near Tahrir Square in Cairo, on November 23, 2011. #

A protester overwhelmed by tear gas, center, is aided by two men on a motorcycle during clashes with Egyptian riot police in Cairo, on November 22, 2011. #

Protesters and police throw stones at each other during clashes near Tahrir Square in Cairo, on November 23, 2011. #

Protesters carry an injured comrade during clashes in a side street near Tahrir Square in Cairo, on November 23, 2011. #

A wounded Egyptian protester reacts as a medic treats him in Cairo, Egypt, on November 21, 2011. #

A man in a face mask looks in on a makeshift medical center in Tahrir Square, on November 22, 2011, in Cairo, Egypt. #

A protester throws a tear gas canister back at riot police during clashes near Tahrir Square, on November 22, 2011. #

A protester gestures toward Egyptian riot police during clashes near Tahrir Square, on November 23, 2011. #

Protesters take cover from riot police during clashes in a side street near Tahrir Square in Cairo, on November 23, 2011. #

A riot policeman points shotgun at protesters during clashes near Tahrir Square in Cairo, on November 23, 2011. #