CAIRO — Interim President Adly Mansour called for restraint and ordered a judicial inquiry into the killings. Significantly, the statement from his office echoed the military's version of events, noting that the killings followed an attempt to storm the Republican Guard's headquarters.
Prosecutors in Cairo also ordered the closure of the Brotherhood party's headquarters amid investigations into a cache of weapons found there, according to the official Middle East News Agency.
El-Tayeb, the sheik of Al-Azhar also called for an independent investigation into the shooting and for the release of all those detained in recent days, referring to five Brotherhood leaders detained since Morsi's fall.
Morsi supporters have been holding rallies and a sit-in outside the Republican Guard building and elsewhere around Cairo since the military deposed Morsi on Wednesday. The military chief replaced Morsi with an interim president until presidential elections are held. The transition plan is backed by liberal and secular opponents of Morsi, and had been also supported by the ultraconservative Islamist Al-Nour party and both Muslim and Christian religious leaders.
Al-Nour party spokesman Nader Bakkar said on his Twitter account his party is withdrawing its support for the transition plan in response to the "massacre."
Morsi's supporters refuse to recognize the change in leadership and insist Morsi be reinstated, and have vowed to continue their sit-ins outside the Republican Guard building as well as at a nearby mosque.
Morsi's opponents are also holding rival rallies. They say the former president lost his legitimacy by mismanaging the country and not ruling democratically, leading to a mass revolt that began June 30, the first anniversary of Morsi's assumption of power.