Rigidity of codimension two indefinite spheres

We describe all isometric immersions f:S_n^sS_sⁿ+2/S_sⁿn–s4, whenever the set of totally geodesic points does not disconnect S_sⁿ, where S_n^sdenotes the complete n-dimensional indefinite Riemannian space form of constant positive curvature 1 and signature s.