VATICAN CITY — Pope Francis will declare the sainthood of Blessed Jacinta Marto and Blessed Francisco Marto, two of the three shepherd children who saw Mary in Fatima, Portugal, in 1917.

The date was announced April 20 in an "ordinary public consistory," a meeting of the pope, cardinals and promoters of sainthood causes that formally ends the sainthood process.

Addressing the assembly, Cardinal Angelo Amato, prefect of the Congregation for Saints' Causes, noted that of the future saints considered at the consistory, five were children or young teenagers.

"In our time, where young people often become objects of exploitation and commerce, these young people excel as witnesses of truth and freedom, messengers of peace (and) of a new humanity reconciled in love," the cardinal said.

At the consistory, the pope also set Oct. 15 as the date for the canonizations of two priests and two groups of martyrs, including Blessed Cristobal, Blessed Antonio and Blessed Juan — also known as the "Child Martyrs of Tlaxcala" — who were among the first native converts in Mexico. They were killed between 1527 and 1529 for refusing to renounce the faith and return to their people's ancient traditions.

Pope Francis will preside over the canonization ceremony of the Fatima visionaries on his visit to Fatima May 12-13.

The pilgrimage will mark the 100th anniversary of the Marian apparitions, which began May 13, 1917, when 9-year-old Francisco and 7-year-old Jacinta, along with their cousin Lucia dos Santos, reported seeing the Virgin Mary. The apparitions continued once a month until Oct. 13, 1917, and later were declared worthy of belief by the Catholic Church.

A year after the apparitions, both of the Marto children became ill in an influenza epidemic that plagued Europe. Francisco died April 4, 1919, at the age of 10, while Jacinta succumbed to her illness Feb. 20, 1920, at the age of 9.

Francisco and Jacinta's cause for canonization was stalled for decades due to a debate on whether non-martyred children have the capacity to understand heroic virtues at a young age. However, in 1979, St. John Paul II allowed their cause to proceed; he declared them venerable in 1989 and beatified them in 2000.

The children's cousin entered the Carmelites. Sister Lucia died in 2005 at the age of 97. The diocesan phase of her sainthood cause concluded in February and now is under study at the Vatican.