Egyptian news site Ahram Online says the army is building a huge barricade to block the ongoing throng of protesters, who are demonstrating against the US embassy in Cairo:

Clashes between protesters and Egyptian Central Security Forces continued near the US embassy in Cairo’s Garden City district into the early hours of Friday morning as demonstrators insisted on voicing their rage over a film produced in the US that mocks Islam and the Prophet Mohamed.  Members of the military have begun constructing a concrete barricade on a street leading to the American embassy in downtown Cairo, as fierce clashes between dozens of protesters and Egypt’s security forces continued through Thursday night in the vicinity.

In this video below, you can see the clashes, and the construction of the wall.