The Francis Scott Key Bridge in the US city of Baltimore collapsed after a large ship collided with it on March 26, US media reported.
The Maryland Transportation Authority posted on social media platform X that all lanes were closed in both directions due to an "incident" on the bridge and that traffic was being redirected.
Up to 20 people are feared to be in the water.
"We understand up to 20 individuals may be in the Patapsco River right now as well as multiple vehicles," Kevin Cartwright of the Baltimore Fire Department told CNN, adding officials were dealing with a "mass casualty multi-agency incident."
Videos of the incident, showing the moment of collapse, were widely shared on social media.
(With inputs from AFP)
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