Here are two security camera videos. You can see the truck suddenly appearing and being struck. The crossing has crossbucks and appears to have a stop sign. After train stops, advance the video to just before the end to see the flash of the explosion and the shockwave moving the camera.
Video Showing Truck Occupying Crossing
In the second video you can see the camera shake - presumably the vibration of the collision - followed by the appearance of the two locomotives in emergency. The second car appears to be derailed - possibly caused by slack action or the truck slamming into its side. Again advance the video to the end to see the explosion.
Train in emergency / formation of fire and explosion