CAIRO — Clashes erupted Sunday across much of Egypt between security forces and supporters of ousted President Mohammed Morsi, leaving 51 dead, as rival crowds of supporters of the military and backers of Mr. Morsi poured into streets around the country to mark a major holiday.
Street battles raged for hours in some neighborhoods of Cairo as Morsi supporters fired birdshot and threw firebombs at police, who responded with gunshots and tear gas.
In some cases, pro-military crowds set upon supporters of the former president, with both sides pelting each other with rocks.
By late evening, several parts of the city resembled combat zones, with fires burning and the crack of gunfire piercing the air, thick with tear gas. Streets were strewn with debris.
The Health Ministry reported 40 people killed in Cairo and 11 others killed in areas outside the capital, with more than 240 people injured.
The Interior Ministry, which is in charge of the police, said 423 Morsi supporters were detained nationwide.
The clashes took place on the 40th anniversary of the start of the 1973 Mideast war with Israel, a holiday that the military-backed government had wanted to use to pay tribute to the armed forces, whose chief ousted Mr. Morsi in a popularly supported coup July 3.
The clashes were the latest chapter in the turmoil roiling the country since the ouster in February, 2011, of longtime ruler Hosni Mubarak and are certain to set back efforts by the government to revive the economy, especially the vital tourism sector, and bring order to Cairo’s streets.
The scene of the fighting contrasted sharply with a carnival-like mood in Cairo’s central Liberation Square, where thousands of military supporters waved Egyptian flags, blew whistles, and touted posters of army chief Gen. Abdel-Fattah el-Sissi.
Earlier, soldiers had barricaded entrances to Liberation Square with barbed wire and armored personnel vehicles. Metal detectors were installed at the entrances and demonstrators pouring into the square were searched by troops.
Late on Sunday, General el-Sissi and interim President Adly Mansour attended a fireworks extravaganza at a military-owned stadium in the eastern part of Cairo.
General el-Sissi’s predecessor, Field Marshal Hussein Tantawi, was among those attending the ceremony, making his first public appearance since Mr. Morsi removed him and his chief of staff, Sami Anan, in August last year.