The authorities say the detainees will be held for 15 days for questioning. Another 50 people are also under investigation. At least two people died in fighting between Muslims and Coptic Christians after a Coptic worshipper was stabbed to death in church. Armed men then attacked three Coptic churches in Alexandria. Egyptian officials blamed the attacks on extremists, but Coptic Christians said the government was not doing enough to protect them. Coptic Christians make up 10% of the Egyptian population and have complained of harassment and discrimination. Some Copts argue that previous attacks on them have gone unpunished or have drawn light sentences. Most Christians in Egypt are Copts - Christians descended from the ancient Egyptians. Their church split from the Eastern Orthodox and Roman Catholic churches in 451 AD because of a theological dispute over the nature of Christ But it is now, on most issues, doctrinally similar to the Eastern Orthodox church. Copts and Eastern Orthodox churches will mark Easter next Sunday. BBC