"I went over there, and sure as anything, it was gone, the whole bridge was just like, there was nothing there."

Jayme Krause was working a nightshift at an Amazon office in Baltimore when she and her coworkers felt a "hard rumbling" in the early hours of Tuesday (March 26).

What she experienced was a container ship smashing into the four-lane Francis Scott Key Bridge in darkness.

The bridge collapsed and sent cars and people plunging into the river below.

Paul Wiedefeld is the Secretary of Maryland Department of Transport.

"At this time this is an active search and rescue mission. We know there were individuals on the bridge at the time of the collapse, working on the bridge, contractors for us."

ABC News, citing an unclassified U.S. intelligence report, said the ship "lost propulsion" as it was leaving port and the crew on board notified Maryland officials they had lost control of the vessel.

Tuesday's disaster may be the worst U.S. bridge collapse since 2007.

Maryland Governor Wes Moore declared a state of emergency to quickly deploy federal resources to deal with emergency.

Baltimore Police Commissioner Richard Worley said there was no indication of terrorism.

Traffic was suspended at the Port of Baltimore until further notice, according to Maryland transportation authorities.

It is the busiest U.S. port for car shipments, handling more than 750,000 vehicles in 2022, according to port data.

David Knight is a specialist advisor at the Institute of Civil Engineer in the UK.

"It's extremely unusual to have a bridge collapse caused by a ship impact. And we do get instances of ship, impact on piers. But normally piers are designed to accommodate to, a certain level of impact from ships."

The ship was identified by LSEG ship tracking data as a Singapore-flagged container ship, the Dali.

Synergy Marine Group, which manages the ship, said all its crew members had been accounted for and there were no reports of any injuries.

Maersk said in a statement that the Dali was chartered by the shipping company at the time of the incident.