Whenever fires, accidents, wrecks, explosions, crimes, riots, or other emergency situations where life, limb, or property may be endangered may cause persons to collect on the public streets, alleys, highways, parking lots, or other public area, the chief law-enforcement officer of any locality or that officer’s authorized representative who is responsible for the security of the scene may establish such areas, zones, or perimeters by the placement of police lines or barricades as are reasonably necessary to (i) preserve the integrity of evidence at such scenes, (ii) notwithstanding the provisions of §§ 46.2-888 through 46.2-891, facilitate the movement of vehicular and pedestrian traffic into, out of, and around the scene, (iii) permit firefighters, police officers, and emergency medical services personnel to perform necessary operations unimpeded, and (iv) protect persons and property. Any police line or barricade erected for these purposes shall be clearly identified by wording such as “Police Line — DO NOT CROSS” or other similar wording. If material or equipment is not available for identifying the prohibited area, then a verbal warning by identifiable law-enforcement officials positioned to indicate a location of a police line or barricade shall be given to any person or persons attempting to cross police lines or barricades without proper authorization. Such scene may be secured no longer than is reasonably necessary to effect the above-described purposes. Nothing in this section shall limit or otherwise affect the authority of, or be construed to deny access to such scene by, any person charged by law with the responsibility of rendering assistance at or investigating any such fires, accidents, wrecks, explosions, crimes or riots. Personnel from information services such as press, radio, and television, when gathering news, shall be exempt from the provisions of this section except that it shall be unlawful for such persons to obstruct the police, firefighters, or emergency medical services personnel in the performance of their duties at such scene. Such personnel shall proceed at their own risk.