Complex sentence: Two of the shooters were dressed as uniformed policemen, while the others wore suits, ties, overcoats and hats, according to witnesses who saw the "police" leading the other men at gunpoint out of the garage after the shooting.
Split into simpler sentences: Two of the shooters were dressed as uniformed policemen, while the others wore suits, ties, overcoats and hats. Witnesses saw the "police" leading the other men at gunpoint out of the garage after the shooting.