Church attacks spark anger.
Egypt's Coptic Christians have protested in the city of Alexandria to demand greater protection following knife attacks at three churches.
Hundreds rallied with banners reading: "Stop the persecution of Copts."
One person was killed and several others injured in the attacks during Friday Mass.
The interior ministry said the assaults had been carried out by one "deranged" man but earlier police reports talked of three simultaneous attacks.
Christians make up 10% of the Egyptian population and have complained of harassment and discrimination.
Egypt's opposition Muslim Brotherhood endorsed the Christians' protest, calling the incident very sad news.
The interior ministry named the assailant as Mahmoud Salah-Eddin Abdel-Raziq, 25, and said he was "psychologically disturbed".
It said the man attacked two churches and was arrested as he tried to enter a third.
But police told the AP news agency that three men had been detained in simultaneous incidents and that an attempt to attack a fourth church had been foiled.
The ministry said five people had been injured, the police as many as 16.
About 600 Copts protested outside one of the churches attacked - Saints Church - holding banners with slogans such as "Until when?" and "Hosni Mubarak, where are you?" referring to the nation's president.
One woman worshipper, Nadia Lofti, said: "We cannot enter their mosques and kill them, yet they can come to our churches and kill us. Where are the police and the government?"
Some Copts argue that previous attacks on them have gone unpunished or have drawn light sentences.
Witnesses said the churches only had one guard each on Friday.
A doctor told AP that one policeman refused to fire on an attacker, saying he did not have orders.