When I did my Forklift operator course, we were explained about the Centre of Gravity, in the vehicle
IMG source: Occupational Health and Safety Blog -https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQK3M8xmQLW-tAkC_wDi_ZZMIeUzBVxWCPMNVs9rP8jV8A_x5Lt2qQDgAQ&s=10
I believe, when the SUV, smashed into that appears to be a bit "overloaded" Truck's front left side, it lost its Centre of Gravity and went out of balance and collapsed on top of the SUV
Possibly some other Elakiriyan with Physics/ Automotive knowledge can explain better..