  We study hypersurfaces in the pseudo-Euclidean space $\mathbb{E}^{n+1}_s$,
which write as a warped product of a $1$-dimensional base with an
$(n-1)$-manifold of constant sectional curvature. We show that either they have
constant sectional curvature or they are contained in a rotational
hypersurface. Therefore, we first define rotational hypersurfaces in the
pseudo-Euclidean space.
