Rescue teams were combing rubble for victims yesterday after three buildings, one of them 20 storeys high, collapsed in downtown Rio de Janeiro, injuring at least five people.

The collapse, apparently caused by structural problems, came as Brazil races to complete preparations to host the 2014 World Cup and 2016 Summer Olympics, which it hopes will highlight its emerging economic and political prowess.

“Three buildings collapsed: a 20-storey building, a 10-storey building and a smaller building of three or four floors,” said Rio Mayor Eduardo Paes.

The disaster took place near the municipal theatre on the city’s Cinelandia square, a historic district that is bustling by day but nearly deserted at night.

A mountain of rubble filled the street, and thick dust covered the cars nearby.

The tallest building had housed several law offices, and construction work was being carried out on two separate floors.

A bank branch and a restaurant were located on the first floor of one of the collapsed buildings, but it was not immediately clear if the two businesses were open at the time of the incident.

Health Secretary Sousa Aguiar said five people were in hospital under observation, adding that the office buildings would have been largely deserted during the night-time collapse.

Witnesses reported hearing an explosion and described scenes reminiscent of the September 11 terror atrocity, with walls of dust and debris.

Allesandro da Silva Fonseca, who was briefly trapped in an elevator while he tried to escape with four other construction workers, said he almost suffocated from the dust.

“I was out of air. I could not breathe,” he said by mobile phone. All five workers later managed to escape, but it was not immediately clear if they were the same victims referred to by health officials.

Dozens of firefighters and emergency personnel rushed to the scene and were combing through the rubble with search dogs through the night.