A crane collapsed at the ground which will host the tournament's first game, with the number of casualties still unknown
The incident occurred on Wednesday, damaging three huge metallic parts of the ground and destroying part of the stadium's structure.
It was initially stated that three people had died in the accident, but Corinthians late confirmed that there had been two fatalities, named as Fabio Luiz Pereira and Ronaldo Oliveira dos Santos.
Goal Brazil spoke to stadium worker, who did not want to be identified, expressed concern that further incidents could take place because of the crane collapse and was mortified by the death of his colleagues.
"I was a little far from the place of the accident, but what I know is that that would've been the last piece to be installed in the stadium structure," he told reporter Fernando Ahuvia.
"We were lucky that several workers weren't there at the moment, because it happened during lunch break.
"The structure fell and initiated a cascade effect. We felt a strong tremor and that's worrisome. It could've affected another structures.
"I'm really sad. Some of the Corinthians' fans are also here, around the stadium, and they are crying with what happen. I'm a Corinthians fan and I know how passionate we are, but the most important thing is the lives of the people."
The Sao Paulo fire department are currently looking for survivors and wounded in the Itaquerao, with work suspended and Odebrect, the company in charge of construction.
The stadium was intended to host the opening game of next summer's World Cup, though Thursday's accident could cast its completion in time for the tournament into doubt.
This is the third fatal incident in the building of World Cup 2014 stadia - the first at the Estadio Nacional Mane Garrincha in June 2012 and the second in March this year at the Arena Amazonia, which both involved a worker falling from a height.