Pope Francis kicked off a whirlwind final full day in Ecuador on Tuesday with an open-air Mass in the capital sandwiched between meetings with bishops, indigenous groups and students and capped by a visit to a famed Jesuit church.

Francis arrived at Quito's Bicentennial Park to cheers from a half-million people, some 300,000 of whom camped out overnight to score a good spot. They were rewarded with a pre-dawn deluge that sent some 20 people to paramedics with hypothermia, city operations director Cristian Rivera said. But the sun broke out as Francis arrived on his popemobile to do a tour through the grounds, with fans tossing confetti on him as he zoomed by.

"The joy at seeing the pope gives us the warmth we need," said Abel Gualoto, a 59-year-old seafood vendor as he rubbed his cold hands together to try to stay warm.

After the Mass, Francis in the afternoon heads to Quito's Catholic University for a meeting with students and professors that is likely to show the unpredictable pope at his best: Francis often goes off-script when he engages with young people, all the more so in his native tongue. Francis then heads to a Quito church for an encounter with business leaders, people involved in the arts and indigenous groups.

History's first Jesuit pope ends his busy day with a visit to the Church of the Society of Jesus, known locally as Iglesia de la Compania. The Jesuit church, a gem of Spanish Baroque, is one of the oldest and most well-known in Ecuador. It houses a painting of the Virgin Mary that was said to shed tears in 1906.

The 78-year-old pontiff, who has only one full lung, appears to be holding up well at the start of his eight-day, three-nation South American tour despite the 2,800-meter (nearly 9,200-feet) altitude of Quito and a day spent in the scorching sun of coastal Guayaquil. He had so much energy he slipped out again for a second night Monday to greet well-wishers who gathered outside the Vatican ambassador's residence where he is staying.

"It's always surprising what the pope can do at his age," said the Vatican spokesman, the Rev. Federico Lombardi. He noted that several people in the Vatican entourage awoke Monday with headaches due to altitude sickness, but not the pope.

"He has said it's God's way of helping him do his ministry, his service," Lombardi said.

Francis received a hero's welcome Monday in Guayaquil, Ecuador's biggest city, as he celebrated the first public Mass of a South American tour that will later take him to Bolivia and Paraguay. He told hundreds of thousands of faithful their families are the bedrock of society but need to be supported better and strengthened.

Crowd estimates varied, with the government spokesman putting it at around 550,000 while Lombardi said it was "plausible and honest" to say 1 million people were on hand.

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Associated Press writer Frank Bajak contributed to this report.