The attack comes just ahead of demonstrations planned to take place across Cairo to press for the cancellation of postponement of Egypt’s constitutional referendum set for Saturday.
The assailants entered the square from the Abdel Money Riyad Street and Qasr Al Nil openings and proceeded to shoot protesters with pellet guns and throw Molotov cocktails at them.
According to physician Hassanein Abu El Hasan, who works in a makeshift clinic in the square, the injuries included pellet bullet wounds in the arms and feet. One protester was also hit in the head.
Protesters have occupied Tahrir Square, the epicentre of the Egyptian revolution, since President Morsi’s controversial constitutional decree issued 22 November, in which he put his decisions above judicial review and sacked the prosecutor-general.
While the decree has been amended, the referendum, in which Egyptians will accept or reject the newly-drafted constitution, is still scheduled for 15 December, much to the anger of the opposition who are highly unsatisfied with the final draft.
The Muslim Brotherhood has called for pro-constitution demonstrations in Nasr City, a densely-populated area in northeast Cairo.
The opposition, meanwhile, has organized six marches across Cairo, which will head to the presidential palace in nearby Heliopolis.
Rival protests are set to sweep the streets of Cairo on Tuesday over a bitterly divisive referendum on a new constitution.
The dueling demonstrations, which reportedly resulted in nine people being hurt early Tuesday when unknown attackers fired at protesters camping at Tahrir Square in central Cairo, has prompted Egyptian President Mohamed Mursi to order the army to help “preserve security”.
The rival protests have been organized by Islamists backing Mursi and the largely secular opposition, raising fears of street clashes like ones last week in which seven people were killed and hundreds injured.
Mursi’s decree instructs the military to fully cooperate with police “to preserve security and protect vital state institutions for a temporary period, up to the announcement of the results from the referendum.”
Army officers “all have powers of legal arrest,” it says.
The military, which has urged dialogue and warned it “will not allow” the political crisis to deteriorate, has for several days kept tanks and troops deployed around Mursi’s presidential palace.
On Tuesday, police cars surrounded the Square, the first time they had appeared in the area since Nov. 23, shortly after a decree by the Islamist president giving himself sweeping temporary powers touched off widespread protests.
The unknown attackers also threw petrol bombs which started a small fire, witnesses said. Many of the protesters, awakened by the noise, chanted: “The people want the downfall of the regime.” Recorded recitations of the Quran were played over speakers in the Square, according to Reuters.
Leftists, liberals and other opposition groups have called for marches to the presidential palace in the afternoon to protest against the hastily arranged referendum on a new constitution planned for Saturday, which they say is polarizing the country.
Islamists, who dominated the body that drew up the constitution, have urged their followers to turn out “in millions” the same day in a show of support for the president and for a referendum they feel sure of winning and that critics say could put Egypt in a religious straitjacket.
The elite Republican Guard has yet to use force to keep protesters away from the palace, now ringed with tanks, barbed wire and concrete barricades, but a decree issued by Mursi late on Sunday gives the armed forces the power to arrest civilians during the referendum and until the announcement of the results.
Cairo schools informed parents they would be closed as a precaution on Tuesday.
A group of senior judges on Monday said pro-Mursi Islamist protesters would have to lift a week-long sit-in outside the constitutional court before they would consider overseeing the referendum.
If the charter is rejected, Mursi has promised to have a new one drawn up by 100 officials chosen directly by the public rather than appointed by the Islamist-dominated parliament.
But analysts said still-strong public support for Mursi and the Brotherhood’s proven ability to mobilize at grassroots level would likely help the draft constitution be adopted.
If that happens, warned Eric Trager, analyst at the Washington Institute for Near East Policy, it would “set up the country for prolonged instability,” he told AFP news agency.
Leftist politician Hamdeen Sabahy, one of the most prominent members of the National Salvation Front opposition coalition, said Mursi was driving a wedge between Egyptians and destroying prospects for consensus.
As well as pushing the early referendum, Mursi has angered opponents by taking sweeping temporary powers he said were necessary to secure the country’s transition to stability after a popular uprising overthrew autocratic former president Hosni Mubarak 22 months ago.
“The road Mohamed Mursi is taking now does not create the possibility for national consensus,” said Sabahy.
If the constitution was passed, he said: “Egypt will continue in this really charged state. It is certain that this constitution is driving us to more political polarization.”
The National Salvation Front also includes Nobel Peace Prize laureate Mohamed ElBaradei and former Arab League chief Amr Moussa.
The opposition says the draft constitution fails to embrace the diversity of 83 million Egyptians, a tenth of whom are Christians, and invites Muslim clerics to influence lawmaking.
But debate over the details has largely given way to noisy street protests and megaphone politics, keeping Egypt off balance and ill-equipped to deal with a looming economic crisis.
Mahmoud Ghozlan, the Muslim Brotherhood’s spokesman, said the opposition could stage protests, but should keep the peace.
“They are free to boycott, participate or say no; they can do what they want. The important thing is that it remains in a peaceful context to preserve the country’s safety and security.”
The army stepped into the conflict on Saturday, telling all sides to resolve their disputes via dialogue and warning that it would not allow Egypt to enter a “dark tunnel”.
The continuing disruption is also casting doubts on the government’s ability to push through tough economic reforms that form part of a proposed $4.8 billion IMF loan agreement.