FÁTIMA, Portugal — Pope Francis canonized two Portuguese shepherd children during a Mass on Saturday, a century after the children and their cousin said they first saw the Virgin Mary here.

The children, Jacinta and Francisco Marto, along with an older cousin, Lúcia de Jesus dos Santos, told skeptical elders that they had witnessed six apparitions of the Virgin between May 13, 1917, and Oct. 13, 1917, when Jacinta was 7, Francisco was 9 and Lúcia was 10, according to the Vatican.

After the Roman Catholic Church here validated the children’s visions, it turned Fátima into Portugal’s main pilgrimage site. The site is nowadays visited by more than five million people a year, many crawling on their knees the last few yards to a shrine of the Madonna.

Organizers had expected as many as one million people to attend the Mass. In the end, 500,000 came, according to the Vatican, a drop that some attributed to the overcrowding concerns that the pontiff’s visit had generated.