Pope Francis in Brazil: Bomb scare, protests in first 24 hours of papal visit (VIDEO)

The visit of Pope Francis to Brazil has generated at least two major security scares only hours after the pontiff began his first official trip abroad.

Brazilian police found a small homemade explosive in a parking garage in the city of Aparecida ahead of the 76-year-old Pope's visit there later this week, Reuters reported.

Separately, thousands of people mobbed the papal vehicle after it became stuck behind buses and taxis when his driver made a wrong turn in downtown Rio de Janeiro, the Associated Press reported.

Pope Francis' visit to what the CIA Fact Book lists as the world's most populous Catholic country has been greeted with mass celebrations. 

However, it also comes amid growing economic and social dissatisfaction in Brazil. June saw the biggest mass protests in two decades, with more than 1 million Brazilians rallying against rising prices, corruption and public services among other issues.

According to Channel 4 News, violent protests broke out in front of Rio de Janeiro's Guanabara government palace on Monday less than an hour after Francis left the venue following his official welcome ceremony.

Riot police fired rubber bullets with around 300 protesters who began hurling firebombs at them.

Meanwhile, local dignitaries, including President Dilma Rousseff, greeted Francis at the start of the week-long gathering for World Youth Day.

More than 1.5 million pilgrims are expected to join in the celebrations, the highlight of which is Francis' July 22-28 visit.

According to the AP, Francis simply smiled Monday as thousands of people rushed his car Monday while it was stuck in traffic.

He had made authorities nervous by deciding to leave his armored "Popemobile" behind to cross the city.

He said:

"I have learned that, to gain access to the Brazilian people, it is necessary to pass through its great heart; so let me knock gently at this door. I ask permission to come in and spend this week with you. I have neither silver nor gold, but I bring with me the most precious thing given to me: Jesus Christ!"

The crowd got close enough to touch the Pope along parts of the route that were not lined with fencing. 

Compounding the fears of Vatican and Brazilian plainclothes security, Francis rolled down his window and touched those who reached inside, even kissing a baby handed in to him by a woman.