A man with a knife attacked worshippers at Coptic churches in this northern Egyptian city Thursday, killing a 78-year-old man and wounding five before he was arrested, the government said.

About 600 Copts, mostly young men, later gathered outside the scene of one of the attacks to protest what they viewed as government indifference to the attacks. "Stop the persecution of Copts in Egypt," read one banner. Blood was visible on the steps of Saints Church.

The protesters chanted: "Hosni Mubarak, where are you?" — a reference to Egypt's president. Coptic Christians make up 10 percent of Egypt's 72 million people in the Muslim-majority country.

The attacks came on what is Good Friday for many of the world's Christians. But the Copts and other Eastern Orthodox churches celebrate Easter a week later.

"A citizen attacked three worshippers inside the Mar Girgis Church in al-Hadhra with a knife and then fled and went into the Saints Church, where he attacked three other worshippers and again fled," the Interior Ministry said.

Police arrested him as he tried to enter yet another church, the ministry said.

The Interior Ministry identified the attacker as Mahmoud Salah-Eddin Abdel-Raziq and said he suffered from "psychological disturbances."

Local police said three men were arrested in the attacks that left one dead and 16 wounded. The discrepancies could not be immediately explained.

The United States urged the Coptic and Muslim communities of Alexandria to exercise tolerance and called on the "government of Egypt to investigate these attacks and swiftly bring the perpetrators to justice."

"We condemn these vicious attacks that seem timed to coincide with observance of the Palm Sunday weekend by Egypt's Coptic Christians. This act of violence against worshippers on a holy day for the Christian Coptic Community in Alexandria is unacceptable," said State Department spokesman Sean McCormack.

"We are trying to calm the situation after many of our youth started protesting," said Father Augustinos of the Mar Girgis church where an attack was foiled. "We want to live in peace and tranquility, but these are people who had their family members killed or wounded. We are doing our best."

The semi-official Middle East News Agency identified the victim as Nushi Atta Girgis, 78.

One of the wounded, Kuzman Tawfiq, 69, said he had finished praying in Saints Church and gone outside.

"Suddenly there was a youth holding two machetes and shouting: 'Oh, the prophet of God! Oh, the prophet of God," he said after recovering from surgery.

The assailant slashed Tawfiq in the stomach, forcing him to have surgery to stop the internal bleeding.

Egyptian Christians generally live in peace with the Muslim majority, but occasional sectarian clashes do occur. In October, Muslim militants attacked churches in the Moharrem Bek area of Alexandria protesting the distribution of the DVD that they deemed offensive to Islam. Four people were killed in weeklong riots.

Christians complain that they suffer job discrimination, particularly in the high ranks of the civil service where positions such as general, provincial governor and faculty head are almost invariably held by Muslims.