The bridge, located at 109th Ave and 8th Street, collapsed on a number of cars.
There are reports of numerous people injured in the collapse. At least one person was taken as a trauma alert to the hospital, according to Miami-Dade Fire Rescue.
The 950-ton bridge went up on Saturday. It was then lowered into its final position, just west of 109th Avenue that day.
The main span was built next to Southwest 8th Street.