Dashcam video of the actual collapse at the bottom of this article:
http://www.miamiherald.com/news/local/article206280134.html
Keep your eye on the crane to the left. The lower section of the bridge broke almost directly underneath whatever was hanging from the crane while the top section cracked to the left of the crane. At first glance, I thought there was a person on top of the bridge where the cable attached to it.