Four people have been confirmed dead and 30 others are missing following the collapse of a bridge in Minneapolis in the US state of Minnesota.
The death toll is expected to rise as rescue services search the river for bodies.
Part of the bridge over the Mississippi River gave way during the evening rush hour last night.
Between 30 and 50 vehicles are thought to have slid into the river when the structure buckled.
The bridge is one of the main crossing points between the twin cities of Minneapolis and St Paul.
The 40-year-old steel arch bridge was last inspected in 2006 and no structural problems were found.
Part of the bridge was closed for routine repairs yesterday, and as a result only one lane of traffic was open in either direction when it collapsed at around 6pm local time.
A 2001 report by the Minnesota Department of Transportation concluded that the bridge 'should not have any problems with fatigue cracking in the foreseeable future' and warned against replacing the bridge 'prematurely'.
The bridge, stretching 581m across the river and resting on 14 spans, collapsed in three places.
The Minnesota Governor, Tim Pawlenty, said his thoughts were with the families who were affected by the disaster.
A spokesman for the US Department of Homeland Security said the incident was not terrorism-related.
60 children were travelling on a school bus that was abandoned at the scene, 10 were taken to hospital following the incident.