Conducting materials separate themselves from non-conductors due to the metallic bonds. Those delocalized electrons that are free and drifting randomly throughout a metal are forced to move when an electric field is present, and currents are formed. However, with Gauss's law, remember we only can apply it to electrostatic situations. This is why charges, through polarization, rearrange and give NO E-field inside when we have static charge. Any net charge sits on the outer surface; this is the only way to have equilibrium. Check it out or review it.