Egypt's interim leader has expressed sorrow over the deaths of at least 51 people near a barracks in Cairo, urging restraint amid ongoing unrest.
Adly Mansour also said he had ordered an investigation into the deaths.
The Muslim Brotherhood says its members were fired on as they staged a sit-in for ousted President Mohammad Morsi, while the army said "terrorists" tried to storm the barracks.
The Brotherhood's political wing meanwhile called for an "uprising."
The Freedom and Justice Party (FJP) — which took nearly half the seats in historic parliamentary elections held in late 2011 and early 2012 — urged Egyptians to revolt against "those trying to steal their revolution with tanks".
Anchor Marco Werman speaks with New York Times correspondent David Kirkpatrick in Cairo