  We study a possible gauge symmetry breaking pattern in an ${\rm SU}(7)$ grand
unified theory, which describes the mass origins of all electrically charged SM
fermions of the second and the third generations. Two intermediate gauge
symmetries of ${\cal G}_{341}\equiv {\rm SU}(3)_c \otimes {\rm SU}(4)_W \otimes
{\rm U}(1)_{X_0}$ and ${\cal G}_{331}\equiv {\rm SU}(3)_c \otimes {\rm SU}(3)_W
\otimes {\rm U}(1)_{X_1}$ arise above the electroweak scale. SM fermion mass
hierarchies between two generations can be obtained through a generalized
seesaw mechanism. The mechanism can be achieved with suppressed symmetry
breaking VEVs from multiple Higgs fields that are necessary to avoid tadpole
terms in the Higgs potential. Some general features of the ${\rm SU}(7)$
fermion spectrum will be described, which include the existence of vectorlike
fermions, the tree-level flavor changing weak currents between the SM fermions
and heavy partner fermions, and the flavor non-universality between different
SM generations from the extended weak sector.
