WATCH: A curfew was imposed overnight in central Cairo and the government is to hold an emergency meeting later today to discuss the unrest.
Egypt's prime minister has appealed for calm after at least 24 people were killed and more than 200 wounded in some of the worst violence since an uprising ousted President Hosni Mubarak in February.
Prime Minister Essam Sharaf, in a televised address, said the violence threatened to throw off course Egypt's post-Mubarak transition to a democratic state.
"These events have taken us backwards and cast panic and fear over the future of the country," he said, "where instead of advancing to build a modern state of democratic principles, we are back searching for security and stability, worrying that there are hidden hands, both domestic and foreign, seeking to obstruct the will of Egyptians in establishing a democracy."
The violence on October 9 pitted Coptic Christians, protesting against an attack on a church, against hard-line Muslims and Egyptian security forces.
Rocks and gasoline bombs were thrown and cars were set alight as the violence later spread from the city's TV center to Tahrir Square.
An armored security van was reported to have struck several protesters.
Tensions between Christians and Muslims have increased since the February uprising.
Christians -- who make up about 10 percent of Egypt's 80 million people -- blame the country's ruling military council for being too lenient on those behind a spate of anti-Christian attacks since Mubarak's ouster.
In related news, Egypt executed today a man for killing six Coptic Christians and one Muslim in a shooting in 2010.
The drive-by shooting, which sparked protests at the time, occurred in the southern town of Nagaa Hamady after Mass on the eve of Orthodox Coptic Christmas, which is on January 7.
compiled from agency reports