Pope Francis opens Holy Week at Vatican on Palm Sunday

Pope Francis celebrates Palm Sunday Mass, in St. Peter’s Square, at the Vatican, Sunday, March 24, 2013. AP

VATICAN CITY  — Pope Francis is celebrating Palm Sunday Mass in St. Peter’s Square, which is filled with thousands of people waving olive branches and palm fronds.

The new pontiff arrived in an uncovered vehicle to start solemn Holy Week ceremonies, which lead up to Easter, Christianity’s most important day.

Francis wore bright red robes over a white cassock and presided over the Mass from an altar sheltered by a canopy on the steps of St. Peter’s Basilica.

Cardinals, many of them among the electors who on March 13 chose the Roman Catholic church’s first Latin American pope, sat in rows for the ceremony held under hazy skies on a breezy day.