Globo television images showed the front of a yellow bus crushed under a large stretch of the fallen highway yesterday, which is about five kilometers from the World Cup stadium.
The health agency of the state of Minas Gerais said two people were killed and 19 injured, up from an earlier toll of one dead and 10 hurt.
A firefighters' spokesman said 13 people were rescued from the bus unscathed but the woman driver was killed.
"The vehicle is completely under" the overpass, he said, adding that the cause of the collapse was not immediately known.
Two trucks belonging to the construction company were also hit but the firm said nobody was inside them at the time, Silva said.
Belo Horizonte's nearby Mineirao Stadium has hosted five World Cup matches and is due to stage a semi-final on Tuesday.