For the second day in a row, Pope Francis has expressed his solidarity with Egypt’s Coptic Christians following an attack on a bus carrying Coptic pilgrims to a remote desert monastery.

Pope Francis led thousands of people in prayer on Sunday for the victims, who Pope Francis said were killed in “another act of ferocious violence” after having refused to renounce their Christian faith.

Speaking from his studio window over St. Peter’s Square, Pope Francis said “May the Lord welcome these courageous witnesses, these martyrs, in his peace and convert the hearts of the violent ones.”

The Islamic State group claimed responsibility for Friday’s attack, which killed 29 people.

On Saturday during a visit to Genoa, Pope Francis prayed for the victims and lamented that there were more martyrs today than in early Christian times.