On the map there are only 2 piers.
They support 3 trusses.
The 2 piers show in the assessment photo, so I doubt they really failed.
Could be that the middle truss collapsed and dragged the end truss toward the center, over the one pier between them.
Oh, ok thanks.
I was only going by the photo above, assuming a design symmetry based on the other two piers/spans.