A home security system includes interactive sensors and a controller in a controlled environment, such as a smart home environment. A central communication device is coupled, wired or wirelessly, directly or indirectly, to the interactive sensors and the controller. The interactive sensors include at least one heartbeat sensor to detect the presence of one or more human bodies and at least one emergency condition sensor to detect the presence of an emergency condition. In some implementations, the controller may determine the number of occupants based on the heartbeats of multiple human bodies detected by the heartbeat sensor. In some implementations, the number of occupants may be determined by the heartbeats detected by the heartbeat sensor in conjunction with one or more other types of sensors, such as a body heat sensor.