Updated

Pope Francis has phoned the Coptic patriarch of Egypt to offer his condolences for the 25 Christians killed in a church bombing in Cairo.

The Vatican says Francis told Patriarch Tawadros II Monday that the Catholic Church was "united in the blood of our martyrs."

Francis has frequently denounced the indiscriminate nature of Islamic attacks against Christians.

The Vatican said Francis promised to pray for Egypt's Coptic community during his Monday Mass for the Virgin of Guadalupe, a feast day that is particularly dear to history's first Latin American pope.

The bomb went off during Sunday Mass at a chapel adjacent to St. Mark's Cathedral, seat of the ancient Coptic Orthodox church. No group has claimed responsibility. Most of those killed were women and children.