The Commissioner, the Deputy Commissioners, the assistant commissioners, the administrators, and law-enforcement officers appointed by the Commissioner and engaged in the enforcement of criminal laws and the laws relating to the operation of motor vehicles on the highways in the Commonwealth shall, before entering on or continuing in their duties, enter into bond with some solvent guaranty, indemnity, fidelity, or casualty company authorized to do business in the Commonwealth as surety, in the penalty of $100,000 and with condition for the faithful and lawful performance of their duties. These bonds shall be filed in the office of the Department and the premiums thereon shall be paid out of the fund appropriated for the enforcement of the laws concerning motor vehicles. All persons injured or damaged in any manner by the unlawful, negligent, or improper conduct of any such officer while on duty may maintain an action on the bond. In lieu of posting bond as provided in this section, any assistant or law-enforcement officer may furnish an adequate liability insurance policy as proof of his ability to respond in damages which may be adjudged against him in favor of any person or persons injured or damaged in any manner resulting from his unlawful, negligent, or improper conduct while on official duty, to the amount of $100,000. The premiums on any such insurance policy or policies shall be paid out of the funds appropriated for the enforcement of the laws concerning motor vehicles. All such bonds and insurance policies shall be approved by the Commissioner.