“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,” said Baltimore Mayor Brandon Scott, calling it “an unthinkable tragedy.”

Sonar has indicated that there are vehicles in the water, where the temperature was about eight degrees Celsius in the early hours of Tuesday (Tuesday night AEDT), according to a buoy that collects data for the National Oceanic and Atmospheric Administration.

Asked if the incident could have been something more than an accident, Baltimore Police Commissioner Richard Worley said: “There is absolutely no indication that there is any terrorism, or that this was done on purpose.”

He said police were working with the FBI and other state agencies to gather intel but again stressed there was no evidence of any foul play.

Maryland Governor Wes Moore declared a state of emergency. He said in a statement the state was “working with an interagency team to quickly deploy federal resources from the Biden administration.”

Earlier, Kevin Cartwright, director of communications for the Baltimore Fire Department, said that several vehicles were on the bridge at the time, including one the size of a semi-trailer.

Cartwright said that some cargo appeared to be dangling from the bridge, which spans the Patapsco River at the entrance to a busy harbour. The river leads to the Port of Baltimore, a major hub for shipping on the east coast. Opened in 1977, the bridge is named for the writer of The Star-Spangled Banner.

Baltimore port’s private and public terminals handled 847,158 autos and light trucks in 2023, the most of any US port. The port also handles farm and construction machinery, sugar, gypsum and coal, according to a Maryland government website.

The port handles imports and exports for major automakers including Nissan, Toyota, General Motors, Volvo, Jaguar Land Rover and the Volkswagen group - including luxury models for Audi, Lamborghini and Bentley.

More than 40 ships remained inside Baltimore port including small cargo ships, tug boats and pleasure craft, data from ship tracking and maritime analytics provider MarineTraffic showed. At least 30 other ships had signalled their destination was Baltimore, the data showed.

The bridge is almost three times as long as the Sydney Harbour Bridge and forms part of a critical road link between Washington, DC, and New York City.

It is part of Interstate 695 and is also used by a large number of Baltimore commuters.

Synergy Marine Group — which owns and manages the ship called the “Dali” — confirmed the vessel hit a pillar of the bridge at about 1:30am while two pilots were in control. It said all crew members, including the pilots, were accounted for and there were no reports of any injuries.

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 Dali 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.

“We are horrified by what has happened in Baltimore, and our thoughts are with all of those affected,” Maersk said.

Tuesday’s disaster may be the worst U.S. bridge collapse since 2007 when the I-35W bridge in Minneapolis collapsed into the Mississippi River, killing 13.

Reuters, AP