Pope Francis presides over Good Friday Colosseum procession

A view of the Colosseum prior to the arrival of Pope Francis to lead the Via Crucis (Way of the Cross) torchlight procession celebrated at the Colosseum on Good Friday in Rome, Friday, March 25, 2016. The evening Via Crucis procession at the ancient amphitheater is a Rome tradition that draws a large crowd of faithful, including many of the pilgrims who flock to the Italian capital for Holy Week ceremonies before Easter Sunday. (AP Photo/Andrew Medichini) (The Associated Press)

Italian Policemen with bomb sniffing dogs patrol inside the Colosseum prior to the start of the Via Crucis (Way of the Cross) torchlight procession on Good Friday in Rome, Friday, March 25, 2016. (Alessandro Di Meo/ANSA via AP Photo) ITALY OUT (The Associated Press)

An Italian Policemen and his bomb sniffing dog patrol outside the Colosseum prior to the start of the Via Crucis (Way of the Cross) torchlight procession on Good Friday in Rome, Friday, March 25, 2016. (AP Photo/Gregorio Borgia) (The Associated Press)

Pope Francis is presiding over a Good Friday procession at Rome's Colosseum. It is his first major Holy Week religious service drawing a large outdoor crowd since the Brussels attacks prompted heightened security across Europe.

Hours earlier, police led explosives-detecting dogs through inspections inside and outside the ancient arena.

Clutching candles and prayer books, thousands of people stood on a cool evening during the torch-lit procession in Rome. Faithful from around the world were taking turns carrying a plain, lightweight cross to recall Jesus' suffering at crucifixion. Police waved metal-detecting wands across pilgrims and searched their bags and knapsacks.

Francis was expected to speak after some two hours of reflections on meditations read aloud. During past Way of the Cross processions at the Colosseum, pontiffs have denounced the world's evils.