What we know about Baltimore bridge collapse
Maryland Governor Wes Moore has declared a state of emergency.
The Baltimore bridge, known more simply as the Key Bridge, was opened in 1977 in honour of Francis Scott Key, a 19th Century Maryland poet who wrote the words for the US national anthem, the Star Spangled Banner.
The bridge was 8,636 feet (2,632m) long and spanned the Patapsco River and Baltimore harbour. The river flows out into Chesapeake Bay, the largest estuary in the US.
It is described as a continuous truss bridge, and its main span of 1,200ft was the third longest of any bridge of its type in the world.
Video footage from the incident appears to show the bridge collapsing instantaneously after the container ship Dali hits one of its pillars. This happened at around 01:30 local time (05:30 GMT) on Tuesday.
