The dynamic response of a cracked magnetoelectroelastic layer sandwiched between dissimilar elastic layers under anti-plane shear and in-plane electric and magnetic impacts is investigated by the integral transform method. Fourier transforms and Laplace transforms are applied to reduce the mixed boundary value problem of the impermeable crack to simultaneous dual integral equations, which are then expressed in terms of simultaneous Fredholm integral equations of the second kind. The stress field, electric field and magnetic field near the crack tip are obtained asymptotically, and the corresponding field intensity factors are further determined. Numerical results show that the stress intensity factors are influenced by the material properties, the electric and magnetic loadings, and the geometry. The crack initiation can be enhanced or retarded depending on the electric and magnetic loading, and the crack may propagate along its original crack line when the criterion of maximum hoop stress is applied.