In Miami, Florida, authorities say at least six people have died after a pedestrian bridge collapsed onto a busy street below, crushing vehicles and trapping victims under huge piles of concrete. At least nine others were injured in the collapse of the nearly 200-foot-long bridge, which was under construction near the campus of Florida International University. Police say they don’t know the cause of the collapse and are enlisting the help of engineers as they investigate the disaster as a possible homicide.