Mario Tama / Getty Images
The pontiff is making his first visit to South America since he was elected. An estimated 2 million people are expected to greet him.
On the day Pope Francis arrived in Brazil for his first overseas trip, authorities detonated a pipe bomb found at a shrine he will visit and the pontiff was caught up in a mob on the busy streets of Rio de Janeiro.
Wearing a plain white robe, carrying his own luggage and flying from Rome to Rio on a no-frills commercial airliner, the Argentine-born Francis touched down in the world’s largest Catholic country on Monday afternoon.
He was first welcomed by Brazilian dignitaries, including President Dilma Rousseff, before taking a motorcade through central Rio, where more than a million people were expected to greet his arrival.
In Rio, after meeting with Rousseff, Francis will walk the Stations of the Cross on Copacabana beach and visit a notoriously violent slum. Francis plans 18 public appearances during his weeklong visit to Brazil for World Youth Day.
As Pope Francis makes his way through the streets of Rio de Janiero for the first time as pontiff, crowds gather around the popemobile to catch a glimpse of the leader of the Catholic Church.
It was learned later Monday that a Brazilian air force detail discovered what was described as a homemade explosive device in a public bathroom at the Aparacida Shrine, a site the pope is to visit on Wednesday, a security source told NBC News.
The device was discovered Sunday during a routine security sweep of the area in anticipation of the papal visit, authorities said. They detonated it on Monday.
The pope rode through Rio in a small silver Fiat with thousands of Brazilians and visiting pilgrims lining the avenues.
At one point as he rode through downtown, the pontiff caused concerns among some onlookers as he was surrounded by a mob who pushed toward the car to take pictures and even tried to touch the pontiff.
Still, he had his window open as he waved to the crowd and kissed babies.
Father Marcio Sergio Queiroz, media coordinator for World Youth Day, told NBC News the pope never felt he was in danger.
"He is the people's pope, and he likes to be in direct touch with the people," Queiroz said. "The warm welcoming was in line with the culture of Brazil."
Yasuyoshi Chiba / AFP – Getty Images
Pope Francis walks out of the plane upon landing at Rio de Janeiro's airport on July 22.
The municipal secretary of transportation, Carlos Osorio, told Brazilian TV that the pope's driver took a wrong turn down the 12-lane Avenida Presidente Vargas, where he was mobbed.
Instead of taking the traffic-free left lanes, the driver turned into the right lanes, which were cluttered with buses and taxis, forcing the pontiff's car to stop.
But while he is traveling with only two Swiss Guards dressed in discreet civilian clothes, the "people's pope" may still have a hard time connecting with the 2 million people expected to greet him.
More than 10,000 army, air force and navy officers, as well as 12,000 regular police and 1,700 elite security forces, are guarding Francis during his visit.
The pope later switched vehicles and rode in his large white open jeep, better known as the "popemobile," through the city where people climbed trees, bus stops and newspaper kiosks to catch a glimpse of his procession. Thousands of people looked down from balconies and windows in the skyscrapers above.
"I felt the call of God," Mari Therese Reyes, 32, of the Philippines who saved up for six months for the trip told The Associated Press. "It's not just to see the pope. It is an encounter with Christ."
Markus Hemmert, a 38-year-old German pilgrim who took three months to cycle to Brazil from Chicago, said: "I love the pope very much."
Since he succeeded Pope Benedict five months ago, Francis has pleased many with a renewed emphasis on traditional Catholic theology, a simple style and his rejection of luxuries.
True to his Jesuit principles, Francis has called for the church to promote social justice and advocate on behalf of the poor.
Francis, 76, told reporters during the plane ride on Monday that the world risks losing a generation of young people to unemployment.
"The world crisis is not treating young people well," said Francis, according to a Reuters report. "We are running the risk of having a generation that does not work. From work comes a person's dignity."
Mary Murray and Claudio Lavanga of NBC News and Reuters and The Associated Press contributed to this report.