The Five Minutes That Brought Down the Key Bridge

“Hold all traffic on the Key Bridge.”

The terse command from an officer in Baltimore’s busy commercial shipping port was one of the first warnings of a disaster that experts now predict will transform shipping on the Eastern Seaboard and change how ships and bridges function around the world. But after the cargo ship Dali lost power early Tuesday, there were precious few minutes to act.

In those minutes, many people — from the ship’s crew, who sent out a mayday signal, to the transportation authority police officers, who stopped traffic heading onto the Francis Scott Key Bridge — did what they could to avert catastrophe, most likely saving many lives.

And yet — no matter what anyone did — several factors made catastrophe all but inevitable. When a ship of this size loses engine power, there is little to be done to correct its course, even dropping an anchor down. And the Key Bridge was particularly vulnerable. As long ago as 1980, engineers had warned that the bridge, because of its design, would never be able to survive a direct hit from a container ship.

The collision and subsequent collapse of the bridge swallowed up seven road workers and an inspector who could not be alerted and pulled off the bridge in time; two were pulled alive out of the water, but four others are still missing and presumed dead. Two bodies were retrieved on Wednesday, authorities said.

Also caught up in the disaster were the ship’s 21 crew members, all from India, who had prepared for a long journey to Sri Lanka on the Dali. While none of them were hurt, they would be held on board for more than a day as the ship sat in the harbor, the ruins of the bridge tangled around it, as authorities began their investigation.

The accident, the deadliest bridge collapse in the United States in more than a decade, will have a lasting impact on the Port of Baltimore, with its 8,000 workers, and industries that rely on the port, which is the leading American hub for auto and other wheeled equipment, said Pete Buttigieg, the U.S. transportation secretary, on Wednesday.

“It’s difficult to overstate the impact of this collision,” Mr. Buttigieg said.

He compared the Dali, roughly as long a city block, to the size of an American aircraft carrier.

“A hundred thousand tons, all going into this pier all at once,” he said of the impact on the bridge support structure.

Officials from the National Transportation Safety Board, which is leading the investigation into the accident, boarded the Dali on Tuesday night to gather documentation. They obtained data from the voyage data recorder, the equivalent of an aircraft’s black box, hoping that it could help investigators determine what led to the accident.

Mr. Buttigieg said that any private party found liable in the accident “will be held responsible.”

It was about half an hour past midnight on Tuesday when the Dali, loaded with cargo containers, departed its dock, guided by two tugboats, as is customary. On board was a local harbor pilot with more than 10 years of experience and deep familiarity with Baltimore’s port, as well as an apprentice pilot in training.

The sky above the Patapsco River was clear and still, lit by a full moon.

At 1:25 a.m., after the two tugboats detached and turned back, the Dali had accelerated to about 10 miles per hour as it approached the Key Bridge. But just then, according to a timeline released by the National Transportation Safety Board on Wednesday, “numerous audible alarms” started sounding on the ship.

For reasons still being investigated, the ship’s powerful propulsion system stopped. The lights flickered out.

The ship had a “complete blackout,” according to Clay Diamond, head of the American Pilots’ Association, who was briefed on the account of the pilot of the Dali. (The chair of the N.T.S.B., Jennifer Homendy, said officials were still trying to determine whether the power failure was complete.)

The harbor pilot noticed the ship starting to swing right, in the direction of one of the piers holding up the Key Bridge. At 1:26, he called for the tugs to return; he urged the captain to try to get the engine back up and directed the crew to steer hard left. As a last ditch measure, at 1:27, he ordered the crew to throw down the port anchor.

One of the tugboats, the Eric McAllister, turned around and raced back toward the ship.

But the failures onboard were cascading. The emergency generator had kicked on, sending a puff of thick smoke belching from the ship’s exhaust stack and briefly restoring the lights, radar and steering. It did not help. With no effective propulsion, the 95,000-ton ship had become an unstoppable object, drifting toward one of the most heavily traveled bridges in Baltimore.

On land, officers with the Maryland Transportation Authority moved swiftly into action. “I need one of you guys on the South side, one of you guys on the North side, hold all traffic on the Key Bridge,” someone is heard saying on the audio recording of emergency radio traffic that night. “There’s a ship approaching that just lost their steering. So until they get that under control, we’ve got to stop all traffic.”

Vehicles were held on either side of the bridge as the ship continued its inexorable drift toward the 1.6-mile-long span.

A minute later, the officers turned their attention to several workers, some of them immigrants from Guatemala, Honduras, El Salvador and Mexico, who were still laboring on the bridge in the chilly darkness, taking advantage of the light traffic at night to fix potholes.

“There’s a crew up there,” one officer is heard saying on the audio recording of the radio exchange between officers. “You might want to notify whoever the foreman is, see if we could get them off the bridge temporarily.”

But even then, the ship was striking the bridge. Almost at once, the pier buckled and collapsed, twisting over the ship, with its cargo containers stacked high on the deck. Then the rest of the bridge went, breaking into sections as it plummeted and splashed into the dark river waters below.

“The size and weight of these ships make them really difficult, even with propulsion, to stop them,” said Stash Pelkowski, a professor at State University of New York Maritime College and a retired Coast Guard rear admiral. With no power, he said, “There was very little the pilot or the crew on the Dali could do.”

The collapse had happened in seconds. Except for the stumps of the piers, the central span of the bridge had plunged into the frigid river — where divers would spend the whole day searching amid twisted metal for bodies — by 1:29 a.m.

“Dispatch, the whole bridge just fell down!” an officer called out. “Whoever, everybody, the whole bridge just collapsed.”

Stray ships had long been seen as a risk to the Key Bridge. Just a few years after the Baltimore structure was constructed in 1977, a vessel crash knocked down the Sunshine Skyway Bridge in Tampa Bay, Fla., killing 35 people.

Officials acknowledged that the Key Bridge would not be able to withstand that kind of direct hit from a heavy cargo vessel. “I would have to say if that ship hit the Bay Bridge or the Key Bridge — I’m talking about the main supports, a direct hit — it would knock it down,” John Snyder, the director of engineering for the state Toll Facilities Administration told the Baltimore Sun at the time.

But building a bridge that could withstand such an impact was simply not economically feasible, he said. When the bridge was built, cargo ships were not the size they are today. A much smaller freighter did hit the bridge in 1980, but the bridge stood strong.

Minutes after the bridge collapsed on Tuesday, both tugboats that had accompanied the Dali arrived on scene, followed soon by the Coast Guard and the Baltimore City Fire Department.

Two of the workers who had been on the bridge were rescued from the water. The others could not be found.

Jack Murphy, who owns Brawner Builders, the company whose workers had been on the bridge, got a phone call about the collapse and raced to the area, about a 30-minute drive away. He stayed by the bridge all night, and eventually began making calls to the men’s families.

Two workers’ bodies were discovered in a red pickup truck found near the bridge debris, police said Wednesday. They were identified as Alejandro Hernandez Fuentes, 35, an immigrant from Mexico, and Dorlian Ronial Castillo Cabrera, 26, a native of Guatemala.

About two miles from the bridge, Andrew Middleton had been lying awake when he heard the crash. He first thought it was thunder, maybe a low-flying jet.

It was only when he awoke a few hours later that he saw the news of the collapsed bridge. “I thought to myself, I was just with those guys yesterday,” he said.

Mr. Middleton, who runs Apostleship of the Sea, a program that ministers to sailors coming through the port, had driven the ship’s captain and a few crew members to Walmart on Monday to stock up on goods for the 28-day voyage ahead — toothpaste, snacks, clothes, Bluetooth speakers.

He recalled the captain telling him their next port was Sri Lanka, but that they were taking a longer route, down around South Africa, in order to avoid recent Houthi attacks on cargo ships in the Red Sea.

Mr. Middleton immediately messaged the crew on WhatsApp after hearing the news on Tuesday, he said, and “they responded within a few minutes saying that everyone was OK,” he said.

Around the site of the bridge collapse, firefighters and rescuers in diving gear were swarming around the shore, followed by news crews. John McAvoy, who owns a nearby restaurant, had driven over with hot meals — chicken, crab balls and pretzel bites — to hand out to the crews.

But by nightfall on Tuesday, officials had called off the rescue efforts and said they would switch to searching for bodies. “The water’s deep, visibility’s low, it’s cold as I-don’t-know-what,” said Kevin Cartwright, a spokesman for the Fire Department.

The signs of all that had changed were only starting to become clear. The U.S. Army Corps of Engineers said it was mobilizing more than 1,100 specialists to clear the wreckage of the bridge and unblock the Port of Baltimore’s shipping lane. In the meantime, Mr. Buttigieg, the secretary of transportation, said the East Coast would have to rely more heavily on ports outside Baltimore.

Mr. McAvoy said the tragedy would ripple over the port for years.

Fishing crews always have found their way home following the Key Bridge, he said. “It’s going to change a lot of things for a lot of people.”

Reporting was contributed by Daniel Victor, Jacey Fortin, Zach Montague, Eduardo Medina, Miriam Jordan and Judson Jones. Susan C. Beachy contributed research.