2 for a differentiated use of force and firearms. These should include the development of non-lethal incapacitating weapons for use in appropriate situations, with a view to increasingly restraining the application of means capable of causing death or injury to persons. For the same purpose, it should also be possible for law enforcement officials to be equipped with self-defensive equipment such as shields, helmets, bullet-proof vests and bullet-proof means of transportation, in order to decrease the need to use weapons of any kind. 3. The development and deployment of non-lethal incapacitating weapons should be carefully evaluated in order to minimize the risk of endangering uninvolved persons, and the use of such weapons should be carefully controlled. 4. Law enforcement officials, in carrying out their duty, shall, as far as possible, apply non-violent means before resorting to the use of force and firearms. They may use force and firearms only if other means remain ineffective or without any promise of achieving the intended result. 5. Whenever the lawful use of force and firearms is unavoidable, law enforcement officials shall: ( a ) Exercise restraint in such use and act in proportion to the seriousness of the offence and the legitimate objective to be achieved; ( b ) Minimize damage and injury, and respect and preserve human life; ( c ) Ensure that assistance and medical aid are rendered to any injured or affected persons at the earliest possible moment; ( d ) Ensure that relatives or close friends of the injured or affected person are notified at the earliest possible moment. 6. Where injury or death is caused by the use of force and firearms by law enforcement officials, they shall report the incident promptly to their superiors, in accordance with principle 22. 7. Governments shall ensure that arbitrary or abusive use of force and firearms by law enforcement officials is punished as a criminal offence under their law. 8. Exceptional circumstances such as internal political instability or any other public emergency may not be invoked to justify any departure from these basic principles. Special provisions 9. Law enforcement officials shall not use firearms against persons except in self-defence or defence of others against the imminent threat of death or serious injury, to prevent the perpetration of a particularly serious crime involving grave threat to life, to arrest a person presenting such a danger and resisting their authority, or to prevent his or her escape, and only when less extreme means are insufficient to achieve these objectives. In any event, intentional lethal use of firearms may only be made when strictly unavoidable in order to protect life. 10. In the circumstances provided for under principle 9, law enforcement officials shall identify themselves as such and give a clear warning of their intent to use firearms, with sufficient time for the warning to be observed, unless to do so would unduly place the law enforcement officials at risk or would create a risk of death or serious harm to other persons, or would be clearly inappropriate or pointless in the circumstances of the incident. 11. Rules and regulations on the use of firearms by law enforcement officials should include guidelines that: ( a ) Specify the circumstances under which law enforcement officials are authorized to carry firearms and prescribe the types of firearms and ammunition permitted;