Protesters fled into side streets to escape the troops in riot gear, who grabbed people and battered them repeatedly even after they had been beaten to the ground, a Reuters journalist said. Shots were fired in the air.
Soldiers pulled down protester tents and set them on fire, local television footage showed.
In Reuters footage, one soldier in a line of charging troops drew a pistol and fired a shot at retreating protesters. It was not clear whether he was using blanks or live ammunition.
Health Minister Fouad el-Nawawy told Egyptian television 10 people were killed and 441 injured. Most those appeared to have died on Friday or in the early hours of Saturday. State media said at least 200 people were taken to hospital.
The army-appointed prime minister, Kamal al-Ganzouri, 78, said 30 security guards outside parliament had been hurt and 18 people had gunshot wounds.
Ten months after a popular revolt toppled President Hosni Mubarak, tensions are running high. The army generals who replaced him have angered some Egyptians by seeming reluctant to give up power. Others back the military as a force for badly needed stability during a difficult transition to democracy.
The army assault on Saturday followed skirmishes between protesters and troops during which a fire destroyed archives, some more than 200 years old, in a building next to Tahrir.
An army official said troops targeted thugs, not protesters, after shots were fired at soldiers and petrol bombs set the archive building ablaze, the state news agency MENA reported.
The French Foreign Ministry said in a statement it was concerned by the violent incidents at Tahrir and condemned the “excessive use of force” against protesters.