When making a hanging cabinet, do you screw sides to the back, or back to the sides, then screw back to wall?

I'll be using those prefinished melamine boards for the cabinet. I'm just concerned that the structure might not be as strong as needed. This is for a hollow block wall in my garage; I intend to make 6 or 7 32-in-x-48-in-x-16-in cabinets hanging about 4 feet from the floor. My concern is that, if a cabinet falls, my car(s) could be crunched! Give me some recommendations even on the anchors that is best to hold the cabinets to the hollow block wall. I would appreciate MORE DETAILS. Please indulge me.When making a hanging cabinet, do you screw sides to the back, or back to the sides, then screw back to wall?
I'd screw the back to the sides and then to attach the cabinets to a cinder block wall I'd prefer to install furring strips of 2';X4'; to the cinder block to better control the anchoring to the cinder block then attach the cabinets to the 2X material. If you don't want the 'Stand-off' involved in using this method I'd use a modified toggle bolt into the hollow portion of the block and use a larger fender washer with the toggle bolt's screw to provide a larger bearing surface. Screw through the cabinet boxes in order to attach one box to the other and you should have no mishaps.When making a hanging cabinet, do you screw sides to the back, or back to the sides, then screw back to wall?
Screw the back to the sides and then the back to the wall.