Resignations rocked the government of President Mohamed Morsi on Thursday as tanks from the special presidential guard took up positions around his palace and the state television headquarters after a night of street fighting between his Islamist supporters and their secular opponents that left at least 6 dead and 450 wounded.

The director of state broadcasting resigned Thursday, as did Rafik Habib, a Christian who was the vice president of theMuslim Brotherhood’s Freedom and Justice Party and the party’s favorite example of its commitment to tolerance and pluralism. Their departures followed an announcement by Zaghoul el-Balshi, the new general secretary of the commission overseeing a planned constitutional referendum, that he was quitting. “I will not participate in a referendum that spilled Egyptian blood,” he said in a television interview during the clashes late Wednesday night.

With the resignations on Thursday, nine Morsi administration officials have quit in protest in recent days. In a day of tension and uncertainty unlike any other since the revolt that overthrew Hosni Mubarak nearly two years ago, state media reported that Mr. Morsi, of the Muslim Brotherhood’s political arm, was meeting with his top advisers and would deliver a public address in response to the clashes. The top scholar of Al Azhar, the center of Sunni Muslim learning that is consideredEgypt’s chief moral authority, urged both sides to pull back from violence and seek “rational dialogue.”