  Consistent interactions among a set of two-form gauge fields in four
dimensions are derived along a Hamiltonian cohomological procedure. It is shown
that the deformation of the BRST charge and BRST-invariant Hamiltonian for the
free model leads to the Freedman-Townsend interaction vertex. The resulting
interaction deforms both the gauge transformations and reducibility relations,
but not the algebra of gauge transformations.
