ALEXANDRIA, Egypt (AP) -- Thousands of police manned barricades around Christian places of worship in this Mediterranean coastal city Saturday after seething sectarian tension spilled into the streets. Egypt's top Muslim and Christian leaders called for calm Saturday, a day after 5,000 Muslim rioters rampaged through two predominantly Christian neighborhoods in Alexandria. The attack on churches and shops constituted Egypt's worst Muslim-Christian violence in five years.The violence sparked clashes with rubber bullet-firing police in which two rioters and two policemen were killed, police and hospital officials said Saturday on condition of anonymity. At least 90 people were injured.The violence followed a week of protests over a stage play deemed offensive to Muslims and performed two years earlier in the St. George's Coptic Church, which was one of seven churches attacked. Although unnoticed at the time, the play was recorded by someone and distributed on DVD recently, angering a large section of Alexandria's predominantly Muslim community.Local political leaders and security officials claim local hard-line Islamists were behind the release of the DVD to coincide with next month's parliamentary elections. The Islamists are being accused of trying to tarnish a Coptic Christian candidate on the ruling National Democratic Party's ticket in Alexandria's impoverished constituency of Ghorbal.But Maher Khalah, one of two Copts running as NDP candidates throughout this mainly Sunni Muslim country, announced later Saturday that he was withdrawing from the election race because of the violence and to prevent any reccurrence."This violence is not about the DVD, it is all about the elections," Khalah told The Associated Press.A senior security official also blamed Islamic extremists for spreading rumors of Copts handing out DVDs showing the play, which is entitled "I Was Blind But Now I Can See." The play tells the story of a young Christian who converts to Islam and becomes disillusioned.Worries of violence spreadingCoptic Christians account for about 10 percent of Egypt's 72 million population and generally live in harmony with the Muslim majority. But violence flares occasionally, particularly in small southern communities. Many Copts also complain of discrimination.Friday's violence was the bloodiest since January 2000, when 23 mainly Christians were killed after an argument between a Coptic shopkeeper and a Muslim customer degenerated into street battles in el-Kusheh, south of Cairo. In a joint-statement, Coptic Orthodox Church head Pope Shenouda III and Egypt's highest Islamic authority, Grand Sheik of al-Azhar Mohammed Sayyed Tantawi, urged Christians and Muslims to resort to dialogue instead of violence."We call on everyone to be calm so we can spread the grace of peace, security and affection among us," the statement said. "If something happened and was misunderstood, then it is our duty to deal with it in the spirit of dialogue and understanding."Shenouda was scheduled to visit Alexandria on Saturday for his annual Ramadan fast-breaking meal with Muslim officials, but canceled because of the violence, church leaders said.The protests over the DVD started October 14, and Islamic leaders accused Copts of distributing DVD copies of the play. The church denied having any role in the production or distribution of the DVDs and refused Islamist demands to apologize.Coptic community leader Kamil Sediq warned that the repercussions of Friday's violence could spread to Cairo and other provinces and stressed that Copts would not be apologizing over the DVD."We're not going to apologize because we don't want it to become a precedent," said Sediq of the Coptic Community Council, a secular body of prominent Copts established in 1874 to oversee affairs of the community. "We did nothing to apologize for."Copyright 2005 The Associated Press. All rights reserved.This material may not be published, broadcast, rewritten, or redistributed.