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A major bridge in the US city of Baltimore has snapped and collapsed after a container ship rammed into it early, sending several vehicles falling into the river.
Baltimore Fire Chief James Wallace said two people have so far been pulled from the water, one in a serious condition and the other not seriously injured.
Wallace said during a press conference about 9.30pm AEDT that authorities "may be looking for upwards of seven people", but warned that number could change.
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There could be as many as 20 people in the water but authorities are unsure if they're people from the ship or cars that fell from the bridge.
"I don't have a number I can tell you, our sonar has detected the presence of vehicles submerged in the water," Wallace said.
Wallace said there is "absolutely no indication" the incident was "an act of terrorism or that it was intentional".
Baltimore Mayor Brandon Scott described it as "an unthinkable tragedy".
"Never would you think that you would see physically see the Key Bridge tumble down like that – it looked like something out of an action movie," he said.
"And you just think about, most importantly, which is what we all should be thinking about right now, nothing but those families and people that are impacted and those people who are risking their lives right now, for not just Baltimore City and Baltimore County but all over the state, to try to save lives.
"That should be our focus – the preservation of life. Because no one wants to see that happen, let alone someone in their family someone that they know, be injured in an incident like this."
Dozens of local agencies are involved in the rescue efforts, bringing in specialist equipment required for a large-scale search.
Wallace said divers would be looking to get into the water but says they face issues including the current, tide coming in and temperatures.
"That adds a bit of a challenge to us also," he said.
"We can certainly dive in these conditions but we have to take a lot of factors into play. The fact that there may be trauma involved, they have been in the water an extended period of time.
"Also remember we're battling darkness so it's quite possible that we may have somebody there that we've not seen yet and as they work closer to the debris field, they'll obviously make those determinations.
"But we're going to rely on the experts which are our divemasters that are here, our dive team, to tell us when they believe we've reached that non-survivable point."
There has also been the odour of diesel fuel across the morning but it was not known if there had an oil spill from the ship.
The vessel appeared to have hit one of the supports of the Francis Scott Key Bridge, in the state of Maryland, causing the roadway to break apart in several places and plunge into the water, according to a video posted on X, formerly known as Twitter.
The ship caught fire, and thick, black smoke billowed out of it.
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"This is a dire emergency," Kevin Cartwright, director of communications for the Baltimore Fire Department, told The Associated Press.
"Our focus right now is trying to rescue and recover these people."
Emergency responders were searching for at least seven people believed to be in the water, Cartwright said, though he said it's too early to know how many people were affected.
He called the collapse a "developing mass casualty event".
He added that some cargo appeared to be dangling from the bridge, which spans the Patapsco River, a vital artery that along with the Port of Baltimore is a hub for shipping on the East Coast. Opened in 1977, the bridge is named for the writer of The Star-Spangled Banner.
Emergency services rushed to the scene about 1.30am (4.30pm AEDT) after reports that a ship leaving Baltimore had struck a column on the bridge, according to Cartwright. Several vehicles were on the bridge at the time, including one the size of a tractor-trailer truck.
The temperature in the river was about 8 degrees in the early hours of Tuesday, according to a buoy that collects data for the National Oceanic and Atmospheric Administration.
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From a vantage point near the entrance to the bridge, jagged remnants of its steel frame were visible protruding from the water, with the on-ramp ending abruptly where the span once began.
The ship is called Dali, according to Cartwright. A vessel by that name was headed from Baltimore to Colombo, Sri Lanka, as its final destination, according to Marine Traffic and Vessel Finder. The ship was flying under a Singapore flag, WTOP radio station reported, citing Petty Officer Matthew West from the Coast Guard in Baltimore.
Baltimore Mayor Brandon M Scott has posted on X that he is "aware of and en route to the incident at the Key Bridge".
https://twitter.com/MayorBMScott/status/1772520713615741111?ref_src=twsrc%5Etfw
"Emergency personnel are on scene, and efforts are underway," Scott said.
"All lanes closed both directions for incident on I-695 Key Bridge. Traffic is being detoured," the Maryland Transportation Authority posted on X.
In 2001, a freight train carrying hazardous materials derailed in a tunnel in downtown Baltimore and caught fire, spewing black smoke into surrounding neighbourhoods and forcing officials to temporarily close all major roads into the city.
The Francis Scott Key Bridge opened in 1977.
The 2.57-kilometre, four-lane bridge extends over the Patapsco River and serves as the outermost crossing of Baltimore's harbour and an essential link of Interstate-695, or the Baltimore Beltway.
– With AP and CNN
More to come.
