Witnesses in Cairo say the Egyptian army has deployed tanks outside the presidential palace, hours after three demonstrators were shot dead in the Egyptian capital during clashes between opponents and supporters of President Mohamed Morsi.

More than 300 people have been injured during the two days of violence.

Reporting from the scene, VOA correspondent Elizabeth Arrott said the violence started Wednesday when Mr. Morsi's Islamist supporters attacked opposition demonstrators angered by the president's decree issued last month. The mandate granted Mr. Morsi sweeping powers that place him above review from the judiciary.

Arrott said most of the presidential supporters in the polarized city were men with beards, typical of members of the Islamist Muslim Brotherhood, while opponents of the president appeared younger and included some women.

“I've seen Molotov cocktails, people armed with iron bars and rocks, some people even pulling branches off of trees in terms of trying to find some kind of weapon to fight with.”

Western media also reported attacks on journalists by Muslim Brotherhood supporters.

The clashes outside the presidential palace marked the first time that political rivals in deeply divided Egypt have battled each other since last year's protests that ousted authoritarian former president Hosni Mubarak.

Separately, three more presidential advisors announced their resignations to protest the decrees granting Mr. Morsi expanded powers. Five of the president's 17 advisors have quit since November 22.

Protests spread to other Egyptian cities, with offices of Mr. Morsi's Muslim Brotherhood set on fire in Ismailia and Suez.

Opposition protesters want Mr. Morsi to abolish his decree, which they see as a power grab. They also oppose a draft constitution they say was drawn up by Islamists without input from secularists and liberals.

A referendum on the constitution is set for December 15.