CAIRO — Dozens of people were reportedly killed in renewed clashes on Friday as thousands of followers of the embattled Muslim Brotherhood took to the streets of Cairo and other cities, facing police officers authorized to use lethal force if threatened. As the Islamists sought to regain momentum after a crushing crackdown by security forces on Wednesday in which almost 640 people were killed, witnesses spoke of gunfire whistling over a main overpass in Cairo and at a downtown square as clashes erupted and police officers lobbed tear gas canisters. Reports of a rising death toll continued throughout the day, with up to 50 dead, a Reuters report said. About 30 bodies were laid out in a mosque in Ramses Square, which was being used as a makeshift field hospital as the injured were brought in from clashes that included gunfire nearby. Fatalities were also reported from protests in other parts of Cairo and in the city of Ismailia near the Suez Canal, and fighting erupted in Fayoum and in Alexandria. In some of the urban battles, it was not immediately clear who was fighting, as gunmen in civilian clothes opened fire. Under military lockdown after the authorities declared a state of emergency, Cairo and other cities had been bracing for more violence after Friday prayer, which has been a central trigger for protest since the wave of turmoil known as the Arab Spring swept through the Arab World beginning in early 2011. In response to the call for what the Brotherhood called a “Friday of rage,” thousands of supporters of the deposed president, Mohamed Morsi, marched from northeast Cairo after the noon prayer, witnesses said, defying a show of strength from the military as they headed toward Ramses Square downtown. For its part, the army and security forces sealed off streets and positioned armored vehicles in Tahrir Square, once the crucible of broad revolt but now a stronghold of Morsi opponents. The violence has alarmed many outsiders stunned by the ferocity of the crackdown and fearful of the potential regional repercussions. The leaders of Germany, France, Britain and Italy urged the European Union Friday to send a united message condemning the violence in Egypt, with Germany Chancellor Angela Merkel calling on Brussels to review its ties with the country. Merkel and French President Francois Hollande called for European Union foreign ministers to meet next week to discuss the nature of the bloc's ties with Cairo. Hollande also spoke with Italian Prime Minister Enrico Letta. The two men called for an end to violence in Egypt and a return to national dialogue and elections, a statement from Hollande's office read. British Prime Minister David Cameron called European Commission President Jose Manuel Barroso to express his concern about the situation, Cameron's office said in a statement. — Agencies See also: • Egypt's tourism faces meltdown • Christians terrified after attacks • Activists worry as Egypt seeks to lionize police