Egypt's top Muslim and Christian leaders appealed for calm as tensions simmered in Alexandria, where some 5,000 Muslim rioters rampaged through two predominantly Christian neighborhoods.

Clashes with rubber bullet-firing police killed two rioters and two policemen, police and hospital officials said Saturday. At least 90 people were injured.

The violence followed a week of protests over the distribution of a DVD of a play deemed offensive to Muslims. St. George's Coptic Church, where the play was performed two years ago, was one of the seven churches attacked Friday.

The play, entitled "I Was Blind But Now I Can See," tells the story of a young Christian who converts to Islam and becomes disillusioned.