A warning system includes one or more modularized alarm subsystems and one or more modularized coupling devices for coupling the alarm subsystems in various manners. The alarm subsystem can include a signaling device and a modularized protection housing. The signaling device operates to provide an alarm in an event of a predetermined situation. The modularized protection housing is configured to mount the signaling device and a coupling device. The coupling device is configured to couple the modularized protection housing with another modularized protection housing therethrough. The modularized protection housing is configured to interchangeably mount different types of signaling devices. The coupling device is further configured to engage another coupling device.