Rescue workers feverishly dug through the wreckage of three downtown buildings Friday, hunting for survivors of a collapse that killed at least 12 people and left 17 more missing, police and municipal authorities said.
Officials believe unauthorized construction work inside a 20-story, 72-year-old building damaged its structure and caused it to crumble, wrenching down two neighboring office buildings of approximately the same age about 8:30 p.m. Wednesday.
Police investigators were interviewing the buildings' tenants and workers, including construction worker Alexandro Fonseca, who was inside an elevator when the tallest building fell, but was pulled from the wreckage alive.
Fonseca told news media gathered at the site that workers had removed several walls on the ninth floor, but said that didn't affect the building's infrastructure. He didn't know if there was an engineer in charge of the project.
Rio's Regional Council of Engineering has said the last time they authorized refurbishing in the building was in 2008. But Mayor Eduardo Paes said a license from city hall is not required for internal construction projects, and the responsibility for such projects lies "exclusively in the hands of workers."
Paes said at a news conference Thursday night that the focus would remain on saving lives and supporting the families of victims. There were 390 workers searching the site, and more than 400 truckloads of debris had been removed, according to the mayor's office.
The head of Rio state's Civil Defense agency said the hunt for survivors will continue for 48 hours more.
City officials said the accident should not cast doubt on Rio's ability to organize and host the upcoming Olympics and World Cup.
"This was an isolated incident that occurred on private property," the mayor's office said in a statement. "The case is entirely unrelated to the preparations for the 2014 World Cup, the 2016 Olympic Games and other events that are already part of the city's calendar."
The families of the missing spent the night in a nearby government building, holding out increasingly slim hopes. Some relatives recognized belongings of victims as workers picked through hundreds of thousands of tons of rubble.
Searchers pulled out Alessandra Alves Lima's purse. Nearby they found the ID card of Edson Menezes. A dentist saw some of the computer material from his office being carried from the site.
Other family members got nothing: no news, no sign of their loved ones.
Afonso Celso Menezes rushed to the site after being alerted by a cousin that the building where his sister worked had crumbled. He didn't want to leave without news of Kelly Menezes. She worked in finance and stayed late closing the month's books in the 20-story building, which housed several accounting offices. By Friday, there was no sign of the 28-year-old.
The office buildings in Rio's historic center were full of a wide range of businesses. Most tenants were gone by the time of the collapse Wednesday, but some had remained to finish leftover work. Several of the missing were in a computing course.