Egyptian police fired tear gas outside Cairo's Coptic cathedral on Sunday after clashes following funeral prayers for four Christians killed in sectarian clashes.
Black-clad riot police pointed at the main gate of the cathedral and fired the tear gas, television footage showed, as Coptic worshippers sought refuge inside the building.
Witnesses said the mourners who were chanting against the ruling Muslim Brotherhood were pelted with stones as they came out of the cathedral.
In a statement, the interior ministry said "a number of mourners began to damage cars in the area which led to confrontations with residents of the area."
Television footage showed scenes of chaos outside the cathedral in the central Cairo neighbourhood of Abbassiya where Coptic bishops had been calling for peace and calm after the killing of the Christians on Friday.
Loud bangs could be heard, as clouds of smoke rose up into the sky and people ran in several directions.
At the service, the congregation chanted against the Muslim Brotherhood of President Mohamed Morsi.
"Leave!" they told Morsi as they held up wooden crosses, television footage showed.
One Muslim was also killed in the clashes which flared on Friday night in Al-Khusus, a poor area in Qalyubia governorate, after a Muslim in his 50s objected to children drawing a swastika on a religious institute.
The man insulted Christians and the cross, and an argument broke out with a young Christian man who was passing by, escalating into a gunbattle between Muslims and Christians in which assault rifles were used.
A priest in Al-Khusus, Suryal Yunan, said attackers torched "parts" of an Anglican church.
Muslims also set a Christian home ablaze and ransacked a pharmacy owned by a Copt, a police official said.
A number of angry Muslim residents tried to surround the town's Mar Girgis church, but the security presence in the area prevented them from doing so.
Both sides then set fire to tyres in the narrow streets where residents live in crowded slum housing.
Christians form between six and 10 percent of Egypt's population of nearly 83 million people.
The country's Coptic Christians and Muslims have clashed on several occasions since the revolution that toppled former president Hosni Mubarak in February 2011.
Around 50 Christians and several Muslims have been killed in the clashes.