The two sides are throwing rocks and some people were bloodied from being beaten with sticks.
Witnesses said Egyptian troops there made no effort to intervene.
The fighting comes as international pressure grows for Mubarak to quit.
The U.S. has told the longtime Egyptian leader that a political transition must begin immediately.
In a televised address last night, Mubarak announced he will not run in Egypt's September elections.
(Copyright 2011 by VERTEXNews/Newsroom Solutions)