VATICAN CITY — Pope Benedict XVI is celebrating Easter Sunday Mass in a packed St. Peter's Square.

Tens of thousands of pilgrims, tourists and Romans are filling the cobblestone square, spilling over into a boulevard leading to the Tiber. Many more are streaming to the square during the midmorning service.

Benedict is celebrating Mass at an altar set up on the steps of St. Peter's Basilica and under a canopy to shield him from rain or sun. Skies over the Vatican are alternating between clouds and peeks of sun. The square is ablaze in color, with rows of yellow daffodils, red-hatted cardinals and tourists waving scarves and flags.

At noon (1000GMT), the pope will move to the central balcony of the basilica to deliver the traditional Easter message. (AP)