Soldiers have baton-charged demonstrators in Cairo's Tahrir Square, two days after street clashes killed 10 people and wounded more than 300.
The army-appointed prime minister, Kamal al-Ganzouri, has blamed the violence on protesters whom he accuses of attacking government buildings.
Hundreds have been injured since the unrest began on Friday, as people demonstrate against continued military rule.
Reuters reports that 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.
Shots were fired in the air.
The violence has marred the first free election most Egyptians can remember and highlights the tensions in Egypt 10 months after a popular revolt toppled President Hosni Mubarak.
Voting in the second round of the election process, as part of a promised transition from army to civilian rule by July, passed off peacefully last week.