Can’t really see enough from the images to tell you what took the lower part of the bridge down. The decking for the lanes closest to the upper burning deck are still intact, but the outer lanes further away from the upper burning deck are down.
So it looks like something separate did the shot on the lower lanes that are down, but I can’t see from enough clear and close perspectives to know much.
Could have been engineers on the footings and columns or accurate missiles from above. Don’t know yet. I’m guessing missiles because of the burning oil cars, but that could possibly have been an engineer job, too (rigged elsewhere, command detonation).
One thing that makes the pictures a little hard to interpret is that the road bridge is built closer to the water and then goes up and over the centers span. On the other hand the raid bridge is built up higher so it has a gradual rise and fall from one side to the other. It appears a truck behind the white truck blew up, destroyed sections of the road bed and exploded upward also setting the rail bridge or the train on it on fire.