Later though, federal police, who are in charge of most of Francis' security, took an upbeat tone.
The agency said a meeting was held with officials from a federal agency overseeing megaevents that Brazil is hosting over the next few years, the highway police who played a role in the motorcade's planning and the Rio mayor's office to evaluate the security provided.
"The evaluation was positive, since there was no incident involving the pope or with any of the faithful," an emailed note read.
It added that the swarming and halting of the motorcade "occurred for a number of reasons, in particular the options of the Vatican itself, concerning the visibility and contact with the pilgrims, expressed by the pope himself. The reduced speed of the motorcade and the vehicle's open window are facts revealing the profile of this pontiff and the encouragement given to the faithful to approach."
Federal police didn't respond to requests for more explanations on how the breakdown in security happened.
Cardinal Timothy Dolan, archbishop of New York and president of the U.S. Conference of Catholic Bishops, is in Brazil and said that in watching the motorcade scene, "I was one of those alarmed myself." He said he was concerned about the pontiff's security.
"I love him and I don't want another conclave. We just finished one so we don't need him to be hurt at all," Dolan said. "So they might need to up the security a bit. But the people of Brazil, the people of Latin America, tend to be enthusiastic by nature, they're just so dynamic in their faith."
Experts said that allowing the pope's car to be swarmed was a grave mistake, but they agreed that the desires of Francis to be out among the public made it difficult to ensure his security.
Paulo Storani, a Rio-based security consultant who spent nearly 30 years on the city's police force and was a captain in an elite unit used to clear out slums, said the events seen Monday had to be analyzed in two ways.
"From the point of view of a head of state, and the pope is a head of state, it's unacceptable what happened. The proximity people had with him was a huge risk, even for his image," Storani said. "On the other hand, in the case of a head of a church and having a charismatic figure like this pope, the situation is different because he wants to be close to the people."
"The police intelligence units have to do a lot more work to detect potential threats to the pope's security and there needs to be a bigger presence of plainclothes officers in the middle of the masses to ensure his security," Storani added.
Ignacio Cano, a researcher at the Violence Analysis Center at Rio de Janeiro State University, said that despite the problems with the motorcade, it's the style and message that Francis wants to get across that is the source of woes for officials.
"It is a difficult situation because authorities want the pope to surround himself with protection, something that goes against the message he wants to impart which is one of simplicity, openness and approximation," Cano said. "In light of this message, isolating him from contact with the people makes no sense at all."
Authorities in Brazil had said about 10,000 police officers and more than 14,000 soldiers would take part in the overall papal security plan, but on Monday virtually no uniformed officers were seen along the motorcade route.
There were few barricades set up along the route and thousands of faithful easily made their way onto streets that were meant to be sealed off from the public. In some places along the route, people could be seen forming "human chains" to keep the crowds at bay.
For a nation that will host the 2014 World Cup and a city that will host the 2016 Olympics, it was a blow for the globe to see television images of the pontiff's car being mobbed and stuck in traffic. The scene comes a month after violent, nationwide protests broke out during the high-profile Confederations Cup soccer tournament, when the nation was also in the global spotlight, unrest that continued Monday outside the government palace where Francis met with top Brazilian leaders.
The papal spokesman, the Rev. Federico Lombardi, made clear that despite the mobs, Francis wouldn't change his decision to use an open-air vehicle and specifically planned to use the open car for the very events expected to draw the largest crowds: a speech on Copacabana beach Thursday, a Way of the Cross procession Friday, and a weekend vigil and Mass in a rural part of Rio.
Lombardi said the pontiff deliberately chose to use the same car he uses in St. Peter's Square, and not the bulletproof popemobile, to be closer to people and interact with them. But that square is a closed and controlled, with Vatican and Italian police ringing the square, the faithful being fenced into pens, and bodyguards trailing the car at all times.
Yet how Vatican and Brazilian authorities decide to organize his security going forward is ultimately not the pope's responsibility, Lombardi said.
"Obviously he desires to have a possibly very direct contact with the people. This is clear, and not a militarization of the situation," said the spokesman. "But the concrete solutions are not chosen by him."
On Wednesday, Francis travels to the town of Aparecida in Sao Paulo state, where the governor said 1,800 police will provide security for the pope.
He's traveling to the town to venerate the Virgin of Aparecida, Brazil's patron saint. About 200,000 faithful are expected to pack into the normally sleepy hamlet where Francis is scheduled to drive about a half mile (1 kilometer) in an open-air vehicle after he lands.
Francis is visiting his home continent for the first time since becoming pontiff, with his visit coinciding with the church's World Youth Day, an event held every three years to bring young Catholics together in an effort to inject new energy in the church.
Associated Press writers Marco Sibaja and Vivian Sequera in Rio de Janeiro and Stan Lehman in Sao Paulo contributed to this report.
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