The Francis Scott Key Bridge disintegrated from the impact of a container ship.
984-foot vessel slammed into a bridge support at a speed of 8 knots, which is about 9 mph.
Rescue crews using sonar detected at least five vehicles in the frigid 50-foot-deep water.
Investigators quickly concluded that it was an accident and not an act of terrorism.
President Joe Biden vowed to rebuild the bridge and send federal funds.