Egyptian troops and security forces attacked thousands of people to force them out of central Cairo's Tahrir Square on Sunday, dpa reported.
Tear gas was used and gunshots were heard, activists said, adding that security forces attacked a field hospital that was set up near Tahrir to help those injured in clashes or choked by tear gas.
Security had also set on fire several tents - put up in the middle of the square - as well as a motorbike, as protesters were trying to reenter Tahrir, chanting "peaceful, peaceful," activists added.