CAIRO — Tens of thousands of Muslim Brotherhood supporters took to the streets today in several Cairo neighborhoods and other towns across Egypt in defiance of a military-imposed state of emergency following the country’s bloodshed earlier this week.

The protesters poured out of mosques after traditional mid-day prayers, responding to the Muslim Brotherhood’s call for a “Day of Rage” as armored military vehicles sealed off main squares in the Egyptian capital and troops with machine guns stood at the ready on key junctions.

Thousands marched on one of the bridges across the Nile River in Cairo, chanting in support of the Brotherhood and against the military coup.

The protests swelled, ignited by the outrage over the deaths of 638 people on Wednesday, when riot police backed by armored vehicles, snipers and bulldozers smashed two sit-ins in Cairo where ousted President Mohammed Morsi’s supporters had been camped out for six weeks to demand his reinstatement.

The assault triggered running battles and deadly clashes between security forces and Morsi supporters elsewhere in Egypt, prompting the Interior Ministry to authorize the use of deadly force against anyone targeting police and state institutions.

Egypt, the Arab world’s most populous nation, has been sharply polarized since the military removed Morsi from power on July 3p.