The 22-strong crew of the Dali container ship first realised something was horribly wrong at 1.24am on Tuesday morning (local time) when they lost power while sailing along the Patapsco River.
The vessel was just 30 minutes into a 27-day journey from Baltimore to Sri Lanka, carrying cargo for the shipping giant Maersk and sailing under the Singapore flag.
But as it approached the Francis Scott Key Bridge, the lights went out. The crew, helmed by two local “pilots” trained to traverse the bay, contacted the coastguard immediately.
Officials on land watched in horror as they realised it was too late to stop the ship drifting. Power returned briefly, then turned off again, and smoke began to billow across the river.
Shortly before 1.29am, the Dali collided with a pillar almost halfway across the bridge, closer to the south bank of the Patapsco.
Within 30 seconds, three of the bridge’s main spans had collapsed, trapping the Dali underneath steel trusses and sending vehicles crossing the river hurtling into the freezing water.
At 1.30am, the Baltimore Fire Department received its first call that the bridge had collapsed, beginning a search and rescue operation that would last hours and involve dozens of local, state and federal first responders.
As initial reports suggested that eight construction workers were on the 1.6-mile bridge when it collapsed, it became clear that the emergency services were in a race against time.
A person can survive in 8C water for around an hour before losing consciousness, and around three hours before dying, according to the National Centre for Cold Water Safety estimates.
But the situation was complicated by the fact that cars could have fallen to the bottom of the 50ft shipping channel that the Dali had tried to traverse. The strong tides of the Chesapeake Bay made the job even harder.
A Baltimore City Fire Department spokesman said responders were dealing with a “developing mass casualty event”.
Jen Woof, who lives on the south side of the river, was woken on Tuesday morning by her son, Jayden, who had crossed the bridge three times – the last time just three minutes before it collapsed.
Jayden had expected to spend the night with his girlfriend on the north side of the river but travelled back home after the pair had an argument.
Feeling guilty about the incident, he drove back to apologise, but his girlfriend sent him away.
The third time he crossed, he was one of the last people to use the bridge.
“He got over the bridge just three minutes before the bridge collapsed,” Woof told The Telegraph.
“He was almost to our house when his girlfriend started texting him to ask if he was okay. He thought she was texting because they were arguing, and she said the bridge had collapsed.
“He came into my house, frantically panicking and yelling for me and showing me a video.”
Johnny Olszewski, the Baltimore County Executive, was woken at 2am by the city’s fire chief, informing him that a major disaster had just unfolded.
“We all awoke this morning to an unspeakable tragedy,” he told a press conference as the sun rose over the banks of the Patapsco.
“We have a long road ahead not just in the search and rescue but in the fallout after this.”
By morning, the search and rescue teams were running a complex operation involving helicopters, dive teams and underwater drones searching the bottom of the river for possible survivors.
Two people were initially recovered from the water – one uninjured and another who was immediately taken to a local trauma centre in a “very serious condition”, said James Wallace, the Baltimore Fire Chief.
At 7.45am, a senior source involved in the operation told The Telegraph: “The odds are not looking good.”
With the search operation still ongoing, talk has inevitably turned to the cause of the collision and the possibility it was deliberate.
On Tuesday morning, the Department of Homeland Security, which deals with the threat of terrorism, said there were “no indications that this was an intentional act”, although FBI officers were on the scene as law enforcement began an initial investigation.
One possible avenue of inquiry is why the ship could not divert its course after it became clear there was a problem.
“I am assuming the first line of investigation will be to understand why the vessel could not avoid the pier when there were no other vessels around,” said Dr Marina Bock, of Aston University.
There will also be calls to examine other bridges of a similar design, which could be vulnerable to similar incidents.
Built in the early 1970s, the Francis Scott Key Bridge did not have many of the safety buffers used on modern bridges, after the Sunshine Skyway Bridge Disaster in Florida.
“Since that time it has been fairly normal to put in what we call dolphins, which are basically fenders that are designed so that the ship hits them and not the bridge,” said Ian Firth, a former president of the Institution of Structural Engineers.
“In the case of Tuesday’s accident, there were some deflector devices in the water, but they don’t appear to be very large and obviously were not sufficient to protect the bridge.
“The ship missed them and hit the bridge itself. What happened after that isn’t surprising.”
The incident ended the life of the bridge, which began construction in 1972 and opened to road traffic in 1977.
Its namesake, Francis Scott, was an American lawyer and amateur poet best known for writing the lyrics to the US national anthem, the Star Spangled Banner.
He lived in Frederick, Maryland, 50 miles west of Baltimore, and wrote the poem after witnessing the bombardment of Fort McHenry by the Royal Navy during the Battle of Baltimore in September 1814.
On Tuesday morning, another Maryland icon, David Simon, paid tribute to the impact the collapse would have on the city he immortalised in the HBO television series The Wire.
“Thinking first of the people on the bridge, but the mind wanders to a port city strangling,” he said on X.
“All the people who rely on ships in and out. The auto-ship imports, Domino Sugar, coal exports, dockwork, whatever container traffic we didn’t lose to Norfolk. Industries. Jobs. Families.”