Rio high-rise collapse highlights World Cup, Olympic concerns (VIDEO)

At least three people are are dead  and 21 have been reported missing after the collapse of an 18-story building in Rio de Janeiro, Brazil, the Associated Press reported.

According to Reuters, an explosion may have triggered the 18-story high-rise in downtown Rio de Janeiro to collapose. 

"It was like an earthquake. First, some pieces of the buildings started to fall down. People started to run. And then it all fell down at once," a witness named Gilbert told Reuters.

Brazilian news agencies suggest four survivors were found, and that as many as 11 people could be inside the wreckage, Reuters said. Agence France-Presse reports said there were 11 victims in the collapse, which happened about 8:40 p.m. local time.

AFP said 30 people were pulled from nearby buildings. A bank and restaurant are in the area, but rescuers are unsure if they were open at the time. The disaster may have been much worse considering the area is a busy daytime center, but empties out after dark.

Raw Video: Building Collapse in Brazil
by associatedpress

The Associated Press said the building was commercial and not residential. An AP reporter at the scene said a strong smell of natural gas remained in the area.

But the city's mayor, perhaps sensitive to criticism about his city's infrastructure, said it was a structural fault.

“There apparently was not an explosion. The collapse occurred because of structural damages,” Eduardo Paes told the AP. “I don’t think there was a gas leak.”

Nelson Tomes, an air-conditioning technician, said he was on the 10th floor of one of the buildings when he heard a “huge noise,” he told iG newswire, according to Reuters.

"I ran down the stairs desperate to escape,” said Tomes, 38. “Just when I left the building, it collapsed. I escaped by the skin of my teeth – it's the work of God,"

Early reports suggested two buildings had collapsed.

The incident illustrates how fragile Brazil’s infrastructure is as it prepares to host the 2014 soccer World Cup and 2016 Olympics, observers say. A gas leak late last year ignited an explosion that killed three.

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