The incident took place on a main avenue, 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 overpass died, said Capt. Federico Pascual of the Belo Horizonte fire department. An official in the mayor's office said a second person died, raising the death toll to two.
The official said 19 people were known to be injured so far. The official spoke on condition of anonymity because he wasn't authorized to talk to the media about the incident.
The overpass collapsed about 3 miles (5 kilometers) from the Mineirao stadium, which has hosted several World Cup matches in recent weeks and is the site of a semifinal match Tuesday.
The overpass "arched over a really busy thoroughfare," Pascual said.
Security camera footage showed heavy traffic on the street below the structure the moment that the overpass collapsed, striking vehicles below and trapping them underneath.