Pope Francis was in critical condition Saturday after he suffered a long asthmatic respiratory crisis that required high flows of oxygen, the Vatican said.

Pope Francis, 88, is in critical condition due to double pneumonia and a severe lung infection. While receiving high oxygen flows and blood transfusions, doctors fear the onset of sepsis, which could further complicate his condition given his advanced age and respiratory issues.

The Vatican on Monday announced the start of nighttime prayers for the health of Pope Francis in St. Peter's Square, and invited Romans and others to join in, as the 88-year-old pontiff battled a complex lung infection and complications.