The incident took place on a main avenue in Belo Horizonte, the expansion of which is one of the infrastructure improvement projects planned for the World Cup, but like most urban transportation projects related to the tournament was not finished on time for the event.
A woman who was driving a commuter bus trapped by the flyover died, said Captain Federico Pascual of the Belo Horizonte fire department. An official in the mayor’s office later said that a second person had died.
The official said 19 people were known to be injured so far.
The overpass collapsed about 6km from the Mineirao stadium, which has hosted several World Cup matches in recent weeks and is the site of a semi-final match on Tuesday.
The flyover “arched over a really busy thoroughfare”, Pascual said.
Security camera footage showed heavy traffic on the street below the structure the moment that the flyover collapsed, striking vehicles below and trapping them underneath.
“When I saw the flyover falling down, I feared the worst would happen, that the bridge would turn on top of our bus,” said Renata Soares, who was sitting at the back of the yellow bus that was crushed.
A World Cup semi-final will be held in Belo Horizonte next Tuesday. The stadium has already hosted five games.
Heavy government spending on the World Cup and long delays in infrastructure projects have spurred violent street protests in Brazil over the past year.
At least seven people were killed working on stadiums prior to the start of the tournament.
Last month, one worker died after a 90-tonne beam fell during the construction of a monorail train project in São Paulo.