More than 100 abandoned buildings in Rio de Janeiro are in such poor condition they are at risk of collapsing, the head of a regional engineering agency said Wednesday, a day after part of a two-story building crumbled in the Olympic city's colonial downtown.

No one was injured in Tuesday's incident, but it was a chilling reminder of the January collapse of three other downtown buildings, which left 17 people dead and five missing and raised questions about Rio's readiness to host the 2014 World Cup and 2016 Olympics.

Agostinho Guerreiro, president of Crea, a public entity representing members of the engineering profession, urged authorities here to act before other buildings tumble down.

"These buildings aren't necessarily going to fall down next week or next month — I don't want to cause public panic — but these 100 or so buildings are definitely in bad enough shape that action is required," Guerreiro told The Associated Press. "We need a public planning strategy that takes these buildings into account and takes concrete steps to preserve them."

About half the at-risk buildings are rambling bourgeois homes from the turn of the 20th century or even earlier, while about 20 were built as recently as the 1980s and abandoned because of money, legal or other problems, he said.

He said that like the buildings in the Tuesday and January incidents, most of the at-risk structures are concentrated in the historic downtown, where gutted, once-grand bourgeois homes are wedged between modern towers.

Other areas of concern are the neighborhood around the legendary Maracana soccer stadium, where the World Cup final is to be held, and the popular nightlife hotspot Lapa, he said. But he added that vast renovation projects under way in and around Maracana should make any risk negligible for the soccer tournament, while bar and nightclub owners' renovation of many old buildings in Lapa had substantially reduced the risk in that area.

Guerreiro said his statistics were based on an exhaustive 2003 study, updated with the findings of the agency's inspectors as they visit building sites to certify the presence a qualified engineer. Crea does not have the right to order its own building inspections, he said.

After the January tragedy, some critics lashed out at what they called a lack of oversight by local authorities, saying it creates a culture of impunity that leads to accidents.

Guerreiro pointed to the private sector, which is largely behind the renaissance in Lapa, as a possible solution to the dangerously dilapidated buildings.

"Happily, the technology is at a point where most of these buildings could be fully recuperated, especially if there's an entrepreneur who'd continue to invest in their maintenance," he said.