A method of processing a hydrocarbon feed may comprise fractionating the hydrocarbon feed into a light stream, a middle stream, and a heavy stream; hydrotreating the heavy stream to form a hydrotreated heavy stream; and feeding the light stream, middle stream, and the hydrotreated heavy stream to a single Fluid Catalytic Cracking (FCC) reaction zone, thereby producing a product stream comprising light olefins. The light stream may be exposed to more severe FCC cracking conditions than the middle stream and the middle stream may be exposed to more severe FCC cracking conditions than the hydrotreated heavy stream, within the same FCC reaction zone. The single FCC reaction zone may be operated in a down-flow configuration and under high severity conditions.