Wreckage from Key Bridge CollapseBefore its collapse on Tuesday, the Francis Scott Key Bridge in Baltimore was considered a seminal engineering accomplishment. The four-lane bridge, which collapsed into the Patapsco River after a vessel struck one of its main support columns early Tuesday morning, was was considered "a major milestone in Maryland’s transportation planning," according to the nonprofit Preservation Maryland. Six missing construction workers on the bridge at the time of the collapse are missing and presumed dead, according to U.S. Coast Guard Rear Admiral Shannon Gilreath. Two others were rescued, one unharmed and the other in "very serious condition,” (POLARIS)