Baltimore's Francis Scott Key Bridge collapsed early on Tuesday after a container ship smashed into a pylon, with the six people missing presumed dead after falling into the frigid water below.
Authorities stopped people from using the bridge after the ship sent out a mayday call, which Maryland's governor said saved lives.
It may be some time before one of the busiest ports on the US Eastern Seaboard can reopen.
What happened in Baltimore?
Shortly after 1am ET (0500 GMT), a container ship named the Dali was sailing down the Patapsco River on its way to Sri Lanka. At 1.24am, it suffered a total power failure and all its lights went out.
Three minutes later, at 1.27am, the container ship struck a pylon of the bridge, crumpling almost the entire structure into the water.
The bridge was up to code and there were no known structural issues, Maryland governor Wes Moore said.
There was no indication of terrorism, police said.
Why did the bridge collapse?
The metal truss-style bridge has a suspended deck, a design that contributed to its collapse, engineers say. The ship appeared to hit a main concrete pier, which rests on soil underwater and is part of the foundation.
Are there any casualties?
Six people are missing and presumed dead, Maryland state police said. Two people were rescued, one unharmed and one critically injured.
A construction crew was fixing potholes on the bridge and eight people fell 185 feet (56 meters) into the river where water temperatures were 47F (8C).
According to research for the Federal Aviation Administration, that is the upper limit of what a human could survive falling into water.
Authorities saved lives by stopping vehicles from using the bridge after the ship sent out a mayday call, the Maryland governor said.
The ship also dropped its anchors to try to avoid the collision.
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 measures 948 feet (289 meters) — as long as three football fields placed end to end — 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.
The same ship was involved in an incident in the port of Antwerp, Belgium, in 2016, when it hit a quay as it tried to exit the North Sea container terminal.
A later inspection in June 2023 carried out in San Antonio in Chile found the vessel had "propulsion and auxiliary machinery" deficiencies, according to data on the public Equasis website, which provides information on ships.
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.
The steel structure is four lanes wide and sits 185 feet (56 meters) above the river.
It opened in 1977 and crosses the Patapsco River, where US national anthem author Francis Scott Key wrote the "Star Spangled Banner" in 1814 after witnessing the British defeat at the Battle of Baltimore and the British bombing of Fort McHenry.
How will the bridge collapse impact the Baltimore Port?
Traffic was suspended at the port after the collision. It is one of the smallest container ports on the Northeastern seaboard, handling about a tenth of the volume that passes through the Port of New York and New Jersey.
The flow of containers to Baltimore can likely be redistributed to bigger ports, said container shipping expert Lars Jensen. However, there could be major disruptions in shipping cars, coal and sugar.
It is the busiest US port for car shipments, handling at least 750,000 vehicles in 2023, according to data from the Maryland Port Administration.
In 2023, the port was the second busiest for coal exports.
It is also the largest US port by volume for handling farm and construction machinery, as well as agricultural products such as sugar and salt.
