BALTIMORE, Maryland: A container ship rammed into a major bridge in Baltimore, Maryland early on Tuesday, causing it to snap and plunge into the river below. Several vehicles fell into the chilly waters and rescuers searched for survivors.

It was also not clear what caused the cargo ship to crash into the Francis Scott Key Bridge long before the busy morning commute in what one official called a 'developing mass casualty event' in a major American city just outside of Washington, D.C. At least two people were rescued, and it was not clear how many more might be in the waters of the busy harbor near a key port.