Postcollision space-times of the Cartesian product form M'xM", where M' and M" are 2-dimensional manifolds, are known with M' and M" having constant curvatures of equal and opposite sign ( for e.m. shock waves) or of the same sign (for gravitational shock waves). We construct here a new explicit postcollision solution of the Einstein-Maxwell vacuum field equations with a cosmological constant for which M' has constant (nonzero) curvature and M" has zero curvature.