Tens of thousands of people gathered at the Vatican Sunday as Pope Leo XIV proclaimed the Catholic Church's first millennial saint, an Italian teenager dubbed "God's Influencer" for his efforts to spread the faith online.

London-born Carlo Acutis, who died of leukaemia in 2006 at the age of 15, was canonized in a solemn ceremony in St. Peter's Square, with his family watching on.

Many young people were among the crowd, which the Vatican estimated at about 60,000, inspired by the example of Acutis's life.