RIO DE JANEIRO - Two construction workers were killed Wednesday during the collapse of a part of the ceiling in Itaquerao stadium in Sao Paulo, which will host the competition' s opening match of the Brazil 2014 World Cup, the Fire Brigade said.

The accident occurred as the last section of the roof over the bleachers was being installed in the Itaquerao stadium, in Sao Paulo.

As the roof was being set up into place, the crane holding the structure broke down, causing the roof to fall over the bleachers. The crane itself also fell on the same place.

According to the local authorities, one of the victims was the worker operating the crane, and the other was a worker who was installing the seats on the bleachers. They was confirmed by Odebrecht building company, responsible of the works at the stadium.

The accident took place at 12:50 local time (15:50 GMT), which is the reason for the few casualties - it was lunchtime and most of the workers were not in their positions.

San Paulo's Public Prosecutor office announced they will inspect the works and will investigate the death of the workers to possibly suspend the building works.

There is still no detailed information on whether the stadium' s structure was compromised.

The final deadline for the stadium to be fully completed had been set for December 2013, and earlier this month the construction company said that 94 percent of the stadium was ready.

FIFA President Sepp Blatter regretted the incident on Twitter and sent his condolences to the family of the dead workers.

Local soccer club Corinthians, the owner of the new stadium, released a statement offering its condolences to the families and declared seven days of mourning in the club.

The Itaquerao stadium will host the six matches of the FIFA World Cup, including the opening match and a semifinal.