Explainer-Why did the Baltimore bridge collapse and what do we know about the ship?

investing.com:

By Lisa Shumaker

(Reuters) — Baltimore's Francis Scott Key Bridge collapsed early on Tuesday after a container ship smashed into the four-lane span, plunging cars into the river. 

WHAT HAPPENED IN BALTIMORE?

At 1:27 a.m. ET (0527 GMT), a container ship named the Dali was sailing down the Patapsco River when it struck a pylon of the bridge, crumpling almost the entire structure into the water. There was no indication of terrorism, police said.

ARE THERE ANY CASUALTIES?

A construction crew was fixing potholes on the bridge and eight people fell into the river where water temperatures were 47 F (8 C). Two people were rescued, one unharmed and one critically injured. Six people remain missing.

WHAT DO WE KNOW ABOUT THE SHIP THAT WAS INVOLVED?

The Dali was leaving Baltimore en route to Colombo, Sri Lanka.

All 22 crew, including two pilots on board, have been accounted for and there were no injuries, the ship's manager, Synergy Marine Group said.

The registered owner of the Singapore-flagged ship is Grace Ocean Pte Ltd, LSEG data show. The ship is 948 feet (289 meters) long and was stacked high with containers.

The ship can hold up to 10,000 twenty-foot equivalent unit, or TEU, a measure of cargo capacity. It was carrying 4,679 TEU.

WHAT DO WE KNOW ABOUT THE BRIDGE THAT COLLAPSED?

The Francis Scott Key Bridge was one of three ways to cross the Baltimore Harbor and handled 31,000 cars per day or 11.3 million vehicles a year.

It is four lanes wide and sits 185 feet (56 meters) above the river.    

It opened in 1977 and crosses the Patapsco River, where U.S. national anthem author Francis Scott Key wrote the «Star Spangled Banner (NASDAQ:BANR)» in 1814 after witnessing the British defeat at the Battle of Baltimore and the British