CAIRO — Gunfire rang out over a main Cairo overpass and police fired tear gas as clashes broke out after tens of thousands of Muslim Brotherhood supporters took to the streets today (Aug 16) across Egypt in defiance of a military-imposed state of emergency following the country’s bloodshed earlier this week.

Fighting first erupted near the Foreign Ministry in the Egyptian capital, according to an Associated Press reporter who saw protesters and people below an overpass throw rocks and bottles at each other. Gunshots rang out during the march. It was not immediately clear who was clashing with whom.

In the northern city of Tanta and Egypt’s second largest city of Alexandria, clashes also broke out between police and Brotherhood supporters. State TV reported that a policeman was shot dead and two others were wounded by gunmen on a checkpoint just outside the capital in an area called New Cairo.

The landmark Tahrir Square in Cairo, where dozens of anti-Brotherhood protesters have been camped out for weeks, was heavily blockaded by tanks and barbed wire to prevent the Islamist marchers getting to the area. The Brotherhood then urged its supporters to head instead to Ramses Square, not far from Tahrir and near Cairo’s train station.

On the overpass leading to Ramses Square, state TV aired video of a man carrying an automatic rifle. The Associated Press reporter there saw one protester wounded by a bullet in the leg.

Earlier today, the protesters poured out of mosques after traditional mid-day prayers, responding to the Brotherhood’s call for a “Day of Rage” as armored military vehicles sealed off main squares in the Egyptian capital and troops with machineguns deployed on key junctions.

The protests were larger than in previous weeks, 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.

Wednesday’s assault had triggered day-long running battles and deadly clashes between security forces and Morsi’s 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 3, following days of mass protests against him and his Brotherhood group.

But Morsi’s supporters have remained defiant, demanding the coup be overturned. The international community has urged both sides in Egypt to show restraint and end the turmoil engulfing the nation.

The Brotherhood’s political wing, the Freedom and Justice Party, said in a statement Friday that the group is not backing down and “will continue to mobilize people to take to the streets without resorting to violence and without vandalism.”

“The struggle to overthrow this illegitimate regime is an obligation, an Islamic, national, moral, and human obligation which we will not steer away from until justice and freedom prevail, and until repression is conquered,” the statement said.

Many Egyptians, while voicing concern over the scale of the police attacks this week, are supportive of the government’s decision to the clear out of the Brotherhood-led sit-ins and protests, which blocked two main intersections in the capital and clogged traffic. AP