Six people are presumed dead after a container ship crashed into a four-lane bridge in the US port of Baltimore, causing it to collapse into the river below.
Authorities are suspending active search and rescue efforts and moving to a "recovery operation", about 18 hours after the collapse.
"Based on the length of time that we've gone in this search... and the water temperatures, at this point we do not believe we're going to find any of these individuals still alive," US Coast Guard rear admiral Shannon Gilreath said.
Search divers are expected to return to the water in the morning with the Coast Guard to remain on the scene overnight.
Two survivors were earlier pulled from the Patapsco River, one in a very serious condition, after huge spans of the 2.6km Francis Scott Key Bridge crumpled into the water on March 26 about 4.30pm AEDT.
Maryland Governor Wes Moore said preliminary investigations indicated it was an accident and there was no credible evidence of terrorism.
The ship's crew had issued a mayday call due to a power issue moments before the crash, allowing authorities to block traffic from entering the bridge.
The bridge was up to code and there were no known structural issues, Mr Moore said.
Work crews had been repairing potholes on the bridge at the time of the collapse which happened about 1am local time, Maryland Secretary of Transportation Paul Wiedefeld said.
A Baltimore City councilwoman earlier told CNN a body had been recovered from the water but has retracted her comments, according to the broadcaster.
Jayme Krause was in the midst of another night shift at her workplace on shore when the cart of packages in front of her shook violently about 2am.
A coworker told her the bridge had collapsed and she ran out to look.
"I went over there, and sure as anything, it was gone, the whole bridge was just like, there was nothing there," she told Reuters in an interview.
"It was a shocking sight to see."
The ship "lost propulsion" as it was leaving port, and crew on board notified Maryland officials they had lost control of the vessel, ABC News reported, citing an unclassified US intelligence report.
Traffic was suspended at the Port of Baltimore until further notice, Maryland transportation authorities said.
It is the busiest US port for car shipments, handling more than 750,000 vehicles in 2022, according to port data.
The closure of one of the US east coast's major ports threatens to disrupt supplies of goods from cars, to coal and other commodities like sugar.
It could create bottlenecks and increase delays and costs on the northeastern seaboard, experts say.
The port handles the most car imports and is among the largest for coal exports.
The ship was identified as the Dali, owned by Grace Ocean Pte Ltd and managed by Synergy Marine Corp.
Synergy said the Dali collided with one of the pillars of the bridge and that all its crew members, including the two pilots, had been accounted for and there were no reports of any injuries.
Baltimore Mayor Brandon Scott described a scene of twisted metal shooting into the sky.
"It was something out of an action movie. It was something you never thought you'd see," he said.
A spokesperson for the Department of Foreign Affairs and Trade said it was trying to find out if any Australians had been affected.
"The Australian embassy in Washington is making urgent inquiries with local authorities to determine whether any Australians have been affected by the collapse of the Francis Scott Key Bridge in Baltimore Maryland," they said.
"Australians in need of emergency consular assistance should contact the Australian Government's 24-hour Consular Emergency Centre 1300 555 135 (within Australia) and +61 2 6261 3305 (from overseas)."
Kevin Cartwright, the spokesman for Baltimore City Fire Department, earlier told Reuters that as many as 20 people could be in the river along with cars and possibly a tractor-trailer.
"This is a mass-casualty, multi-agency event," he said.
"This operation is going to extend for many days."
A live video posted on YouTube showed the ship ploughing into the bridge in darkness.
The headlights of vehicles could be seen on the bridge as it crashed into the water and the ship caught fire.
Tuesday's disaster was the first major collapse of a bridge from a ship impact in about 40 or 50 years, David Knight, a specialist at the Institution of Civil Engineers, told Reuters.
The Dali was chartered by shipping company Maersk at the time of the incident, the Danish company said in a statement.
"We are horrified by what has happened in Baltimore, and our thoughts are with all of those affected," Maersk said.
The Francis Scott Key bridge is a 2.5 kilometre steel bridge that spans the Patapsco River. It's named after the writer of the US national anthem, the Star-Spangled Banner.
Baltimore is about 60km northwest of Washington DC and the 30th-most populous city in the US.
Australian Associated Press
