Egyptian security forces fired shots into the air after clashes broke out between protesters and gangs of armed men Saturday.
The unrest took place in Cairo as about 1,000 demonstrators were marching near the Defense Ministry to press their demands for political reforms.
Witnesses say the protesters were confronted by bands of men who began throwing bottles and stones. The demonstrators fought back. Officials say at least 100 people were hurt in the clashes.
The incident occurred several hours after the head of Egypt's ruling military council said the government was committed to democracy.
Field Marshal Mohammed Hussein Tantawi said the interim government was moving forward with its efforts to build a democratic state that upholds the rights and freedoms of citizens through free and fair elections.
He made the comments in a recorded speech marking the anniversary of a 1952 military coup.
Meanwhile, activists who say they are not satisfied with the pace of reforms continue their vigil in Cairo's Tahrir Square. Some erected tents in the square two weeks ago and said they will stay put until their demands are met.
On Friday, protesters rallied in the square and in cities including Alexandria, where witnesses say the military fired shots into the air to disperse demonstrators.
Some protesters said this week's Cabinet reshuffle stopped short of meeting their demands.
On Thursday, the government swore in a new Cabinet, in which about half of the ministers are new. But some activists wanted Prime Minister Essam Sharaf to replace the key interior and justice ministers, both of whom kept their posts.
Demonstrators have urged military rulers to purge all officials who served under former President Hosni Mubarak from the government and prosecute those linked to violence and corruption.