RIO DE JANEIRO - A wrong turn sent a humble Fiat carrying Pope Francis into the thick of a frenzied Rio crowd Monday, in his first minutes back in South America since becoming pontiff. It was a nightmare for security officials, but for the clearly delighted pope just another opportunity to connect.

Ecstatic throngs forced his motorcade to repeatedly come to a standstill, weeks after violent protests against the government paralyzed parts of Brazil. Francis' driver had turned into the wrong side of a boulevard at one point, missing lanes that had been cleared. Other parts of the pope's route to the city center weren't lined with fencing, giving the throngs more chances to get close, with uniformed police nowhere in sight to act as crowd control.

The three dozen visible Vatican and Brazilian plainclothes security officials struggled to keep the crowds at bay. Francis, however, not only looked calm but got even closer to the people. He rolled down his back-seat window, waved to the crowd and touched those who reached inside. He kissed a baby a woman handed to him.

"His secretary was afraid," papal spokesman the Rev. Federico Lombardi said. "But the pope was happy."

The pope is here on a seven-day visit meant to fan the fervor of the faithful around the globe. That task has grown more challenging as Roman Catholics stray, even in strongholds of the religion such as Brazil, yet it seemed to come easily to Francis even on the drive from the airport to an official opening ceremony.

After finally making it past crowds and blocked traffic, Francis switched to an open-air vehicle as he toured around the main streets in downtown Rio through mobs of people who screamed wildly as he waved and smiled. He left his popemobile - the bulletproof one - in the Vatican garage so he could better connect with people during the church's World Youth Day.

The Vatican insisted they had no concern for the pope's safety as his vehicles eased through the masses, but Lombardi acknowledged that there might have been some "errors" that need correcting.

"This is something new, maybe also a lesson for the coming days," Lombardi said.

Many in the crowd looked stunned to see the pope, with some standing still and others sobbing loudly.

"I can't travel to Rome, but he came here to make my country better ... and to deepen our faith," Idaclea Rangel, a 73-year-old Catholic choked through her tears after the pope passed by.

As many as 1 million young people from around the world are expected in Rio for the Catholic youth fest, a seemingly tailor-made event for the Argentine-born pope, who has proven enormously popular in his four months on the job. But the fervor of the crowds that regularly greet Francis in St. Peter's Square was nothing compared with the raucous welcome in Rio.

Popes generally get a warm welcome in Latin America; even the more aloof Pope Benedict XVI received a hero's welcome when he visited Mexico and Cuba in 2012. John Paul II frequently received rock star treatment, and during one 1996 visit to Venezuela, his motorcade was similarly mobbed when he stopped to greet well-wishers after greeting prisoners.

Outside the Guanabara government palace where the pope was officially welcomed, Alicia Velazquez, a 55-year-old arts teacher from Buenos Aires, waited to catch a glimpse of the man she knew well when he was archbishop of her hometown.

"It was so amazing when he was selected, we just couldn't believe it. We cried and hugged one another," Velazquez said. "I personally want to see if he's still the same man as simple and humble whom we all knew. I have faith that he's remained the same."

Francis displayed that humility in greeting President Dilma Rousseff, saying he understood that to really know Brazilians, one must pass through their heart.

"So let me knock gently at this door," Francis said in Portuguese at the official welcome ceremony. "I have neither silver nor gold, but I bring with me the most precious thing given to me: Jesus Christ."

On the plane en route to Rio, he had lamented that an entire generation of young people risked not knowing what it's like to work thanks to an economic crisis that has seen youth unemployment skyrocket in many European countries while leaving the poor of the developing world behind.

"People get their dignity from work, they earn their bread," he told reporters aboard the plane. "Young people in this moment are in crisis."

Francis arrived at a tense time for Brazil, as the country reels from sometimes violent demonstrations that began last month as a protest against public transport price hikes and mushroomed into a wave of protests against government corruption, inefficiency and spending for the 2014 World Cup and 2016 Olympics.

Those protests continued after Francis' arrival. Police and anti-government protesters clashed outside the government palace. About an hour after the pontiff concluded his short speech, police began cracking down on the protests, firing rubber bullets in an effort to disperse the crowd.

The government spent about $52 million for Francis' visit, but he does not appear to be a focus of protesters' rage.

"We've got nothing against the pope. Nobody here is against him," said Christopher Creindel, a 22-year-old art student and Rio native protesting outside the government palace. "This protest is against our politicians."

Lombardi confirmed that a homemade explosive device was found Sunday by Brazilian authorities in a public toilet near the basilica at Aparecida, a Marian shrine that Francis will visit Wednesday. Vatican security was informed of the device but didn't think it was aimed at the pope, Lombardi said.

"There are no concerns for security. The concerns are that the enthusiasm is so great that it's difficult to respond to so much enthusiasm for the pope. But there is no fear and no concern," he told reporters.

Francis' weeklong schedule underscores his commitment to make his pontificate focus on the poor. He will walk through one of Rio's shantytowns, or favelas, and meet with juvenile offenders, an extension of his call for a more missionary church that goes to the peripheries to preach.

He will also pray at Aparecida, an indication of his strong Marian devotion that is shared in much of Latin America. And, in a rather incongruous matchup, he will preside over a procession re-enacting Christ's crucifixion on the beach at Copacabana, ground zero of Rio's Sin City.

Alex Augusto, a 22-year-old seminarian dressed in the bright green official T-shirt for pilgrims, said Monday that he and five friends made the journey from Brazil's Sao Paulo state to "show that contrary to popular belief, the church isn't only made up of older people, it's full of young people. We want to show the real image of the church."

Yet pilgrims like Augusto are the exception in Brazil and much of Latin America, a region with more faithful than any other in the world but where millions have left the church for rival Pentecostal evangelical churches or secularism.

A poll from the respected Datafolha group published Sunday in the newspaper Folha de S.Paulo said 57 percent of Brazilians age 16 and older call themselves Catholic, the lowest ever recorded. In 1980, when Pope John Paul II became the first pontiff to visit Brazil, 89 percent listed themselves as Catholics, according to that year's census.

Datafolha interviewed 3,758 people across Brazil on June 6-7 and said the poll had a margin error of 2 percentage points.

Associated Press writers Jenny Barchfield, Vivian Sequera and Marco Sibaja contributed to this report.

Nicole Winfield on Twitter: www.twitter.com/nwinfield