LUANDA, Angola (AP) âÄî Hundreds of thousands of Angolans have gathered for an open-air mass that is the last major event of Pope Benedict XVI’s first African pilgrimage. Officials expect 500,000 people while state television says it could be 3 million in this mainly Catholic country. Portuguese news agency LUSA reported at least two people were killed in a stampede at a stadium before the pope addressed young people there Saturday. Vatican officials say the pope will speak about the tragedy. Dozens at Saturday’s event collapsed from heat exhaustion. Sunday’s crowds appear prepared for a stiflingly hot day on the outskirts of the seaside capital of Luanda, with parasols and cooler boxes. Some people spent the night in the open to ensure a sight of the Catholic leader.