The 78-year-old Argentine pope led the world 's Roman Catholics by paying tribute to those killed for their faith . Pope Francis said he was praying for all victims of terrorism and violence in Iraq and Syria as well as a plane crash that left at least 100 people dead on Saturday. Thousands gathered at St Peter 's Squareon the day that marks the start of Holy Week , which ends on Easter Sunday .
The 78-year-old Argentine pope led the world 's Roman Catholics by paying tribute to those killed for their faith . Last month Pope Francis denounced the killing of 21 Egyptian Coptic Christians by Islamic State militants in Libya . Thousands gathered at St Peter 's Squareon the day that marks the start of Holy Week , which ends on Easter Sunday .