Authorities on Tuesday suspended their search for six people missing after a packed cargo ship slammed into a Baltimore bridge, causing it to collapse and blocking one of the busiest US commercial harbors.

“Based on the length of time that we’ve gone in this search, the extensive search efforts that we put into it, the water temperature… at this point we do not believe that we’re going to find any of these individuals still alive,” US Coast Guard Rear Admiral Shannon Gilreath told a press conference as night fell.

All six people were members of a nighttime construction crew who were repairing potholes on the Francis Scott Key Bridge when disaster struck not long after midnight.

“We’re going away from the search and rescue portion to a recovery operation,” said Roland Butler, Maryland’s secretary of state police.

He said the temperatures and currents were making it difficult for divers to continue working underwater, but that boats would continue patrolling overnight.

Video footage showed the packed container ship slamming into one of the bridge’s supports, causing the 1977-built steel structure to then collapse like a deck of cards.