The Vatican says the pope remains in "very serious condition" but is lucid and spent the morning celebrating Mass and receiving some top aides.
Papal spokesman Joaquin Navarro-Valls at one point broke into tears as he told reporters that the 84-year-old pope had been "informed of the gravity of his situation." The pope has decided to remain in his apartment overlooking St. Peter's Square.
The pope suffered heart failure during treatment for a urinary tract infection yesterday and was given cardio-respiratory assistance. His blood pressure remains unstable. But the Vatican denies a news report the pope slipped into a coma.
Thousands of pilgrims gathered in St. Peter's Square to stand vigil for John Paul, many tearfully gazing up at his window.