A construction worker fell to his death Saturday from the roof of a World Cup stadium being built in the jungle city of Manaus, marking the latest setback to hit Brazil before it hosts football's showcase event next year. It was the second death at the Arena Amazonia this year, and the third fatality in a World Cup stadium in less than a month. A few hours after Saturday's death, another worker died of a heart attack while working outside the venue in Manaus, and a local union threatened to start a strike there on Monday to complain about inadequate conditions offered to laborers. In late November, two workers were killed when a crane collapsed as it was hoisting a 500-ton piece of roofing at the Sao Paulo stadium that will host the tournament's June 12 opener. Last year, a worker died at the construction site of the stadium in the nation's capital, Brasilia. Another worker died in April at the new Palmeiras stadium, which may be used for teams training for games in Sao Paulo. Brazil had already made headlines a week ago because of fan violence in the final round of the Brazilian league, and again earlier this month after World Cup organizers announced that none of the six stadiums that had to be finalized by the end of the year would be delivered on time. Andrade Gutierrez, the construction company building the Arena Amazonia, said in a statement Saturday that 22-year-old Marcleudo de Melo Ferreira fell some 115 feet (35 meters) in the early morning accident - the second fatality at the venue since construction began in 2010. Another man died there in March. The 49-year-old man who had a heart attack was paving an area outside the venue when he died. He was working for a construction company hired by local officials, and local media reported that family members complained that he was working seven days a week and there was pressure from his superiors to finish the work on time. After the worker's fall earlier in the day, a local union said it was considering a strike to call attention to inappropriate working conditions. "We need a strike to show what is really happening inside the arena," Cicero Custodio, president of Amazonas state civil construction workers' union, told GloboEsporte.com. The Manaus stadium will host four World Cup matches, beginning with England vs. Italy on June 14. It will also host the United States vs. Portugal on June 22. Most teams were hoping to avoid playing in Manaus because of humid and hot conditions in the jungle city, as well as the increased travel distance. After complaints from England coach Roy Hodgson before the World Cup draw earlier this month, Manaus Mayor Arthur Virgilio said he hoped "to get a better team and a coach who is more sensible and polite." Andrade Gutierrez said the causes of the accident would be investigated but reiterated its commitment to worker safety.