Devices, systems, and methods for responding to emergency situations of infants, children and pets left unattended in a vehicle. The device comprises a control module for short range RF transmission housed in a lightweight, portable unit plugged into a vehicle accessory power outlet. The system may additionally comprise sensors in communication with the module to detect and trigger alarms, including: when a vehicle has been in a collision; whether a child has climbed out of a car seat while the vehicle is in motion; when the temperature within the vehicle is unsafe; whether an infant has been left unattended in a vehicle; and whether children are playing in a parked vehicle (e.g. trunk) in unsafe temperatures. The portable device may also be configured with an “SOS” button housed within a key fob, wristband, or necklace, to transmit GPS coordinates of the wearer in emergency situations (such as kidnappings).