Abstract: A hazard detector device comprises: a smoke detector to detect smoke, and to generate an output indicating that smoke is detected; a wireless receiver to receive, from a remote hazard detector apparatus, an incoming wireless communication signal indicating that the remote hazard detector apparatus detected a hazard; an audible alert generator to generate an audible alert in response to said incoming wireless communication signal; a wireless transmitter to transmit, to a remote alarm device, an outgoing wireless communication signal indicating that at least one of the following conditions exist: (a) the smoke detector of said hazard detector device detected smoke; (b) said hazard detector device received said incoming wireless communication signal indicating the remote hazard detector apparatus detected a hazard.