CAIRO -- Thousands of protesters clashed violently with one another Friday in dueling demonstrations over the performance of Mohammed Morsi, Egypt's first democratically elected president, and the group he once led, the Muslim Brotherhood.
At least 110 people were injured in the melee that underscored how, three months after Mr. Morsi came to office, Egypt's political system has become a rivalry between conservative Islamists who want religion to play a major role in governance and Egyptians who favor a more secular society.
Clashes that began in Cairo's Tahrir Square spread to side streets, where demonstrators fired gunshots and threw sticks, stones, Molotov cocktails and glass bottles at each other. The Brotherhood's Freedom and Justice Party said protesters also burned buses and set a party building ablaze.
Skirmishes between the supporters and opponents of Mr. Morsi began after some demonstrators chanted "Down, down with the supreme guide," referring to the top official of the Muslim Brotherhood, of which Mr. Morsi was a leading member for decades, resigning once he won the presidency.
Brotherhood supporters yelled offsetting chants in support of Mr. Morsi.
Liberal and secular groups had called for demonstrations weeks ago to protest what they said was Mr. Morsi's failure to fulfill promises in his administration's first 100 days. They also demanded more influence over drafting the country's new constitution, increases in the minimum wage and trials of those accused in the killings of protesters during last year's uprising against then-President Hosni Mubarak.
On Wednesday, the Muslim Brotherhood called its own protest after a judge acquitted 24 people of charges that they had participated in or helped plan an incident last year, when Mubarak supporters on camels and horses stormed Tahrir Square, leaving 21 dead and hundreds injured.
The day after the acquittal, Mr. Morsi ordered the prosecutor, Abdel-Meguid Mahmoud, to step down. But he refused to be relieved, even though Mr. Morsi appointed him ambassador to the Vatican.
Secular demonstrators accused the Brotherhood of stepping in to disrupt their protest. "I don't understand why [the Brotherhood] is protesting," said telecommunication engineer Shady Malek, 26. "They have all the legislative and executive authorities."
Brotherhood demonstrators said they were simply showing support for the new president. "I came to support Morsi's decision to dismiss the prosecutor. From day one, we were calling to overthrow the regime, and he is a man of the regime," said Abdel Wahab Seliem, 50, a shop owner. "The will of the people should be above everything."