ALL six people missing after a major bridge in the US city of Baltimore collapsed are presumed dead, authorities have said.

The search for their bodies is now suspended until Wednesday morning local time.

The six disappeared when a container ship lost power and crashed into the bridge early on Tuesday, causing it to snap in several places and plunge into the river below.

Maryland governor Wes Moore said with the ship barrelling towards the bridge at “a very, very rapid speed,” authorities had just enough time to stop cars from coming over the bridge.

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

Two people were rescued from the water, and the remaining six still unaccounted for are believed to have been working on the bridge when it collapsed.

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It tumbled into the water in a matter of seconds — a shocking spectacle that was captured on video and posted on social media. The vessel caught fire and thick, black smoke billowed out of it.

The crash happened long before the busy morning commute in what one official called a “developing mass casualty event”.

A senior executive at the company that employed the workers said they were presumed dead due to the water’s depth and the length of time since the crash.

Jeffrey Pritzker, executive vice president of Brawner Builders, said the crew was working in the middle of the bridge when it came down.

“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.”

Jesus Campos, who has worked on the bridge for Brawner Builders and knows members of the crew, said he was told they were on a break and some were sitting in their trucks when the bridge went down.

“I know that a month ago, I was there, and I know what it feels like when the trailers pass,” Campos said.

“Imagine knowing that is falling. It is so hard. One would not know what to do.”

Brandon Scott, mayor of Baltimore, which is in the state of Maryland, said: “Never would you think that you would see, physically see, the Key Bridge tumble down like that.

“It looked like something out of an action movie,” Scott said, calling it “an unthinkable tragedy”.