Witnesses heard loud bang before the three buildings in central Rio collapsed almost simultaneously
Rescue workers have recovered three bodies from the wreckage of three buildings that collapsed in central Rio .
Six people were pulled alive from the rubble, but at least 16 people were still missing.
Desperate relatives gathered at the scene and outside a nearby hospital searching for information about those inside the buildings when they were reduced to a giant heap of rubble and steel, at about 8.40pm on Wednesday.
"His mobile phone is off," one weeping man, named as Everton, told reporters as he sought news of his father who had been working inside one of the buildings.
The disaster took place next to one of Rio's most famous landmarks – the historic Municipal Theatre, where Barack Obama spoke last March during a bridge-building trip to Brazil – and a few minutes' walk from the downtown Lapa neighbourhood, popular with tourists and music lovers.
In an interview with breakfast TV on Thursday morning, Rio's mayor, Eduardo Paes, refused to "feed speculation" about the causes of the collapse and said rescuers still hoped to locate survivors.
"The hope of finding people alive always exists," he told a special edition of the Bom Dia Rio news programme, which was offering rolling coverage of the disaster. "We have to keep faith until the last possible moment."
According to authorities, the three buildings – with 18, 10 and four floors respectively – collapsed almost simultaneously, sending rubble crashing down into the street and creating a giant cloud of dust and cement.
Witnesses said they heard a loud bang before the buildings crumbled.
Luiz Antônio Jean Trajan, a lawyer who works on the street where the disaster took place, said: "It was like the World Trade Centre. I heard a loud bang and saw everything happen … At least two workers were inside at the time of the tragedy."
"The entire building fell as if it had been imploded," he told the O Globo newspaper.
Another eyewitness, named only as Rodrigo, told Globo TV: "I was having a coffee and I heard a loud noise. It felt like rain was falling. When I looked up it was as if there was a fog obscuring our vision. People started shouting and running. All we could think was about trying to save ourselves. You couldn't see who was beside you. When the fog cleared... we saw the building had collapsed."
As firefighters used diggers and sniffer dogs to search for survivors, reports emerged of one man's miraculous escape.
Alessandro da Silva Franco Santos, a construction worker, said he had dived into one building's ninth-floor lift after realising it was about to collapse. Two hours later he was pulled from the rubble by rescuers.
"When I saw everything collapsing I thought, 'I'm going to die'. I thought, 'Today I won't be going home'," he told local TV outside a hospital where at least six other victims were being treated. "It was horrible."
Grinning, cheek to cheek, Santos added: "I was born again."