Six workers are missing and presumed dead following the collapse of the Francis Scott Key Bridge in the United States city of Baltimore, as authorities called a halt to search-and-rescue efforts.

US Coastguard and Maryland State Police officials said late on Tuesday that search-and-rescue operations had been suspended as dive teams were facing increasingly dangerous conditions in the darkened waters of the Patapsco River.

“At this point, we do not believe we are going to find any of these individuals still alive,” Coastguard Rear Admiral Shannon Gilreath said at a news conference.

State Police Colonel Roland Butler said authorities intended to return divers to the water after sunrise on Wednesday in an effort to recover the deceased’s remains.

Authorities said the Dali cargo ship crashed into the bridge at about 1:30am (05:30 GMT) on Tuesday, catching fire before sinking. In a spectacular moment of destruction caught on video, the bridge buckled and then fell into the water.

Officials initially called the incident a “developing mass casualty event” but said later that eight people were believed to have fallen into the water. Two were rescued, with one in serious condition and one later released from the hospital.

Baltimore Mayor Brandon M Scott and Maryland Governor Wes Moore announced states of emergency for the city and state.

“It looked like something out of an action movie,” Scott told a news conference, calling it “an unthinkable tragedy”.

In remarks after the collapse, President Joe Biden said he planned to visit the site “as quickly as I can”.

He added he would request federal funds from Congress to rebuild the bridge. It had previously served as a vital artery to the northeast region of the US, accommodating 30,000 cars a day.

The Port of Baltimore was also shut down after the crash, bringing one of the country’s busiest maritime shipping terminals to a standstill. Biden described it as the “top port in America for both imports and exports of automobiles and light trucks”.

“This is going to take some time,” Biden said of recovery and rebuilding efforts. “The people of Baltimore can count on us, though, to stick with them at every step of the way until the port is reopened and the bridge is rebuilt.”

Nothing to indicate ‘intentional’

Biden also said there was nothing to indicate the collision was “intentional”. The Federal Bureau of Investigation (FBI) also said earlier in the day there was no credible information to suggest terrorism.

Jennifer Homendy, the chairwoman of the National Transportation Safety Board (NTSB), said a 24-member team from her agency would launch an investigation once search-and-rescue operations are completed.

That investigation will probe both the safety of the ship and the structural integrity of the bridge.

Dali, the cargo ship involved in the crash, was owned by Grace Ocean Private Ltd and managed by the Singapore-based Synergy Marine Group.

The container ship was about 300 metres (985 feet) long and about 48 metres (147 feet) wide. It was travelling at about 8 knots, or roughly 14.8km/hour (9 mph), when it slammed into a pillar of the bridge.

The vessel caught fire after the collision and thick black smoke billowed out of it. The bridge, meanwhile, crumpled like a toy.

Before it buckled, the Francis Scott Key Bridge had stretched 2.6km (1.6 miles) over the Patapsco River, which leads to the Chesapeake Bay and Atlantic Ocean.

Frantic mayday call

Governor Moore said the ship’s crew issued a mayday call moments before the crash took place, reporting an apparent power failure. That call allowed authorities to mostly stop traffic on the bridge.

“These people are heroes,” Moore said of the crew. “They saved lives last night.”

According to radio traffic obtained from Broadcastify.com, a police dispatcher put out a call saying a ship had lost its steering and asked officers to stop all traffic

One officer radioed that he was going to drive onto the bridge to alert a construction crew filling potholes there. But seconds later, an officer was heard saying: “The whole bridge just fell down. Start, start whoever, everybody … The whole bridge just collapsed.”

Six construction workers disappeared in the debris.

Jeffrey Pritzker – the executive vice president of Brawner Builders, the company that employed the workers – said the crew was working in the middle of the bridge and the six missing workers are presumed dead.

“This was so completely unforeseen,” Pritzker said. “We don’t know what else to say. We take such great pride in safety and we have cones and signs and lights and barriers and flaggers. But we never foresaw that the bridge would collapse.”

The executive for Prince George’s County, Angela Alsobrooks, posted on X that police divers were unable to access the area because underwater drones show “an abundance of twisted metal and debris”.

Meanwhile, Jesus Campos, an employee of Brawner Builders, told the Associated Press news agency that he had been told the workers were on break when the bridge collapsed.

Campos had previously worked on the bridge and prayed that his colleagues were not harmed.

“It is so hard for me to describe. I know that a month ago, I was there  and I know what it feels like when the trailers pass. Imagine knowing that it is falling. It is so hard, one would not know what to do,” Campos said.

‘Cathedrals of American infrastructure’

Speaking to reporters on Tuesday, US Secretary of Transportation Pete Buttigieg hailed the Francis Scott Key Bridge as “one of the cathedrals of American infrastructure”.

“It has been part of the skyline for this region for longer than many of us have been alive,” he said.

The bridge opened in 1977 and is named for the poet who provided the lyrics for The Star-Spangled Banner, the US national anthem.

When asked if US residents should be confident in the safety of other bridges in the area, Buttigieg said the collapse was a “unique situation”.

All vessel traffic into and out of the Port of Baltimore remains suspended until further notice, although the facility is still open to trucks.

The White House said it would be monitoring for any disruptions to the US supply change as a result of the collision, which is all but assured to cause a logistical nightmare in the months ahead.

Ryan Petersen, the CEO of Flexport, a supply chain management company, said Americans should expect shortages of goods in the coming weeks. He predicted the collision would create a “vicious feedback loop” that would resonate beyond Baltimore’s economy.

The Port of Baltimore’s private and public terminals handled 847,158 cars 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 the Maryland State Government website.

On Tuesday, Maryland State Senator Johnny Ray Salling warned: “Losing this bridge will devastate the entire area, as well as the entire East Coast.”