US officials are scrambling to get a critical Baltimore port reopened after a bridge collapse. 

A fully-laden container ship lost power and rammed into a support of the Francis Scott Key Bridge. 

They were able to send a distress signal in time for officials to shut the bridge. 

Ninety seconds later it collapsed, and six people remain unaccounted for. 

Baltimore port is one of America's biggest, and US correspondent Richard Arnold told Mike Hosking that it will take a while to get it back in working order. 

He says they will have to clear out all the wreckage from the shallow waters first, which will be a massive job. 

LISTEN ABOVE 

• 'Unthinkable tragedy': Six missing workers presumed dead following bridge collapse
• 6 still missing after Baltimore bridge collapses