Buildings collapse in central Rio - 19 missing

RIO DE JANEIRO, Brazil -- Two high-rising building blocks collapsed in central Rio on Wednesday evening following an explosion.

Rescue crews were able to pull four people alive out of the debris left behind by the two buildings, which reportedly were 10- and 20-storeys high.

Some 19 people were still missing as of the early hours of Thursday morning, with officials assessing the chances of finding more survivors as "very small".

Coronel Sergio Simoes, Rio's civil defense secretary, said he did not believe anyone had survived the tragedy: "We hope there might be an air pocket and that we might find some survivor, but this possibility is lamentably very small."

The cause of an explosion reportedly preceding the collapse of the buildings has yet to be confirmed.

Wednesday's building collapse was the latest in a series of incidents in Rio de Janeiro highlighting the failure of authorities to improve the city's infrastructure amid preparations to host soccer's World Cup in 2014 and the Olympics in 2016.