A merchant, agent or employee of the merchant, who causes the arrest or detention of any person pursuant to the provisions of §§ 18.2-95, 18.2-96 or § 18.2-103, shall not be held civilly liable for unlawful detention, if such detention does not exceed one hour, slander, malicious prosecution, false imprisonment, false arrest, or assault and battery of the person so arrested or detained, whether such arrest or detention takes place on the premises of the merchant, or after close pursuit from such premises by such merchant, his agent or employee, provided that, in causing the arrest or detention of such person, the merchant, agent or employee of the merchant, had at the time of such arrest or detention probable cause to believe that the person had shoplifted or committed willful concealment of goods or merchandise. The activation of an electronic article surveillance device as a result of a person exiting the premises or an area within the premises of a merchant where an electronic article surveillance device is located shall constitute probable cause for the detention of such person by such merchant, his agent or employee, provided such person is detained only in a reasonable manner and only for such time as is necessary for an inquiry into the circumstances surrounding the activation of the device, and provided that clear and visible notice is posted at each exit and location within the premises where such a device is located indicating the presence of an antishoplifting or inventory control device. For purposes of this section, “electronic article surveillance device” means an electronic device designed and operated for the purpose of detecting the removal from the premises, or a protected area within such premises, of specially marked or tagged merchandise.