The Itaquerao stadium, due to host the opening match of the 2014 World Cup, was 94% completed at the time of the accident.
The damage could delay the completion of the stadium, which must meet FIFA's December deadline.
More top news
Andrew Taylor and Timmy Donovan set upon PC Neil Doyle after spotting him on a Christmas night out.
Hundreds of people have been forced to evacuate their homes in northern California as wildfires ripped through dry brush and scrub oak.
A year-long US-led bombing campaign against Islamic State has left the group no weaker, American intelligence agencies have said.