The head of Rio de Janeiro’s regional engineering agency says the Olympic city has at least 100 abandoned buildings that run the risk of collapse. Agostinho Guerreiro is president of Rio state’s Crea engineering agency. He says the at-risk buildings are mostly concentrated in older districts, such as the city’s colonial downtown. Others dot residential neighborhoods, mostly in the poorer northern district. Guerreiro’s comments Wednesday came a day after part of a historic two-story building collapsed in downtown Rio. No one was injured in the incident, but 17 people died in the January collapse of three other downtown buildings. The collapses are an embarrassment for local authorities in Rio as the city gears up to host the final matches of the 2014 soccer World Cup and the 2016 Olympics.