Cairo's Tahrir Square went on lock down Friday after Egyptian police fired tear gas at protestors.
Clashes broke out during a march by thousands of supporters of ousted Islamist President Mohammed Morsi.
Protesters encircled security forces and army troops guarding the square from two main entrances, one near Egyptian museum and a second from the square's southern edge.
That prompted riot police to fire volleys of tear gas to send the demonstrators away.
All the way to Tahrir Square, the protesters' chants against the military sparked clashes with civilians believed to be supporters of the military. Shots were fired and rocks were thrown.
"We will go protest and take all streets possible," said Mohammed Said, 45, during a march from the Dokki neighborhood to Tahrir. "We will get in Tahrir at any price."
The Brotherhood is demanding that Morsi be reinstated as president and that the Morsi-era constitution be restored.