A car bomb explosion outside a Christian church in Egyptian city Alexandria has killed 21 people and has injured more than 50.The latest official casualty figures came from the Health Ministry. Egypt’s media Al Ahram quoting police, reported that car bomb exploded when worshippers were emerging from a New Year's Mass from the Saints Church in Sidi Bishr, Alexandria.The injured include police officers and three men guarding the church. The police said they were still investigating whether the car had been rigged with explosives or if a bomb had been placed under it. Reports say that demonstrators took to the street after the incident.An earlier toll from the interior ministry said seven people had been killed and 24 wounded.