Several people died when a pedestrian bridge spanning eight lanes of traffic collapsed at a university in Miami, Florida, trapping people and cars shortly before 2pm Thursday, local time.
The under-construction bridge was intended to connect Florida International University in Miami-Dade County with the city of Sweetwater. It was swung into place days ago and was not yet open to foot traffic.
The Miami Herald reported the bridge gave way suddenly while a traffic light for motorists on the road was red and the concrete span fell on top of a row of stopped vehicles.
Authorities said eight vehicles were trapped and more than 100 emergency services personnel were involved in an extensive search and rescue mission.
Rescuers expected to be at the site throughout the night.
There were reports of workers on the bridge when it collapsed. Paramedics had transported eight people.
It is not known if any survivors are still trapped under the rubble.
CBS Miami showed footage of firefighters climbing on the wreckage of the bridge while paramedics treated several people on the road.
Pillars on the south side of the bridge were still standing but the rest of the bridge was on the ground. Cranes could be seen at the site.
Firefighters were on the scene and medics were treating injured people. Emergency personnel appeared to be trying to work their way through a hole in the top of the bridge.
Florida Highway Patrol Lieutenant Alex Camacho earlier said there were 'several fatalities'.
“There are five to six vehicles underneath that are crushed.”
Workers at the scene told local media the bridge was undergoing some sort of stress test when it collapsed.
FIU News reported last week the main 53-metre, 950-tonne section of the bridge was lowered into place over the eight-lane road on March 10.
Florida International University president Mark B. Rosenberg said at the time the university was about 'building bridges and student safety' and the project 'accomplishes our mission beautifully'.
“We are filled with pride and satisfaction at seeing this engineering feat come to life and connect our campus to the surrounding community where thousands of our students live.”
The company building the bridge, Munilla Construction Management, said in a statement on Thursday local time: 'We are all devastated and doing everything we can to assist.
'Our family's thoughts and prayers go out to everyone affected by this terrible tragedy.
'The new UniversityCity Bridge, which was under construction, experienced a catastrophic collapse causing injuries and loss of life.'
The statement said MCM would conduct a full investigation to determine exactly what went wrong and would co-operate with investigators.
The university said on social media: 'We are shocked and saddened about the tragic events unfolding at the FIU-Sweetwater pedestrian bridge.
'At this time we are still involved in rescue efforts and gathering information. We are working closely with authorities and first responders at the scene.'
FIU senior vice-president of finance Ken Jessell told reporters: 'Our hearts are broken over this tragedy ... We are going to do anything and everything we can to assist [the victims] during this process.'
The bridge was being constructed to allow safe passage for students.