A newly installed pedestrian bridge over a major road in Miami collapsed on Thursday, killing six people and trapping several cars underneath.
The footbridge, which connected Florida International University to a student housing area, went up less than a week ago but was not yet operational.
Ten people were taken to hospital, Miami-Dade police spokesman Alvaro Zabaleta said, with emergency crews working all through the night at the scene.
At least eight cars were trapped when the 950-ton (tonne) bridge suddenly gave way on Thursday, Miami-Dade Fire Rescue Division Chief Paul Estopinan said.
The bridge was suspended from cables which had come loose and while they were being tightened, the whole thing collapsed, Florida Senator Marco Rubio wrote on Twitter.
Police detective Juan Carlos Llera said, "it sounded like an explosion. A huge bang."
The bridge had only been installed on Saturday, ahead of its planned opening in 2019.
The university had only recently been celebrating the construction of the bridge across a busy and dangerous section of highway that students said had been the scene of accidents.
"Continuing to monitor the heartbreaking bridge collapse at FIU - so tragic," President Donald Trump wrote on Twitter.
"Many brave First Responders rushed in to save lives. Thank you for your courage. Praying this evening for all who are affected," he said.
Photographs: Joe Skipper/Reuters
