"At this moment, I would like to remember those who spend their time in the service of our brothers and sisters in difficult or risky environments. Let us pray especially for the Spanish missionary sister, Sister Isabel, who was killed two days ago in the capital of Haiti," the Pope said Sept. 4 before concluding the canonization Mass for St. Teresa of Calcutta.

Sister Isabel Sola Matas of the Congregation of the Religious of Jesus and Mary was killed in Port-au-Prince.

Investigators said two unidentified men shot her twice in an attempted robbery after she left a bank, reported Agence France-Presse. Another person with her was shot but survived and was being treated at a local hospital.

Pope Francis called for an end to "such acts of violence and greater security for all" in Haiti. He asked the people present in St. Peter's Square to "also remember other sisters who have recently suffered violence in other countries."

In a statement released Sept. 3, Sister Monica Joseph, superior general of the congregation, announced Sister Sola Matas' death, saying she was "saddened, pained and still in shock."

"Please, pray for Isabel, her family and for our sisters in Haiti, the United States and Spain," the superior general said.