No person except the attorney or attorneys for the Commonwealth, a stenographer or operator of a recording device appointed by the attorney for the Commonwealth, the witness under examination, an interpreter, if needed, a parent, guardian or custodian of a minor witness or other person under disability, and the grand jurors shall be present while the grand jury is in session. No person other than the grand jurors shall be present while the grand jury is deliberating or voting. Any person violating this rule may be held in contempt of court.