U.N. Secretary-General Ban Ki-moon has voiced alarm at the turmoil in Egypt, following another tense day when security forces raided a Cairo mosque to end a standoff that included exchanges of gunfire.

In a statement late Saturday, Mr. Ban urged an end to violent protests and cited an "excessive use of force" in handling them. He said preventing more deaths should be the Egyptians' top priority at this time.

Earlier, security forces took control of the al-Fatah mosque, where many supporters of ousted President Mohamed Morsi sought refuge after Friday's bloody "Day of Rage."

Arab news media showed security forces shooting at the mosque, and scenes of chaos inside the building as people took cover. Police cleared hundreds of protesters from the area.

Egypt's interim government accused Mr. Morsi's Muslim Brotherhood of provoking the violence.

Egypt's state news agency says some 250 Brotherhood supporters are under investigation in relation to the turmoil.

More than 700 people have been killed in recent days in Egypt. The deadliest day was Friday, when clashes in Cairo and other cities left 173 people dead and more than 1,000 injured, according to the government.

A government spokesman said 57 police officers were among those killed on Friday.

The pro-Morsi National Alliance for Supporting Legitimacy put Friday's death toll at 213. The government has accused the Muslim Brotherhood of inflating the casualty toll.

The Muslim Brotherhood, which accuses the government has killed thousands of Egyptians this past week, says its protests will continue.