MADRID -- Pope Benedict XVI urged more than 1.5 million young people to become missionaries for the faith Sunday, giving them words of encouragement as he ended a glitch-marred church youth festival and announced that the next edition will be in Rio de Janeiro in 2013.
Pope Benedict told the pilgrims at a Madrid airfield hosting World Youth Day that they should not keep their faith private but participate fully in the life of their parishes and remain in communion with the church.
"So do not keep Christ to yourselves! Share with others the joy of your faith," he said.
Hours earlier, a fierce thunderstorm during a prayer vigil at the airfield had forced him to cut short his remarks and slightly injured six people when a tent collapsed.
Some makeshift chapels set up on the field's perimeter were also damaged, prompting organizers to announce Sunday morning over loudspeakers that not everyone would be able to receive Communion at the Mass.
Neither police nor the regional government have provided an official crowd count, but Vatican spokesman the Rev. Federico Lombardi said it was entirely "credible" that more than 1.5 million people took part.
Pope Benedict arrived at the field Sunday morning and processed through the crowd in his white popemobile to the cheers and chants of the flag-waving pilgrims. Spain's King Juan Carlos and Queen Sofia were on hand.
In remarks to the crowd, the Pope said he hoped the young people had managed to get some sleep despite the weather. On Saturday, 2,500 had been treated for mostly heat-related problems amid temperatures that soared to 104, organizers said.
This is his third World Youth Day, the gathering of young Catholics from around the world once every three years that was launched a quarter-century ago by Pope John Paul II in a bid to reinvigorate and spread the faith among the young.
At the end of Sunday's Mass, he announced the next World Youth Day will be in Rio in 2013 -- a year early to avoid conflicts with the 2014 World Cup in Brazil -- and said he hoped to attend.