Abstract: A security system which monitors a number of vehicles each of which includes an immobilizer and a transceiver. The system includes a number of security stations which detect signals emitted by vehicles when an unauthorized at, e.g. breaking and entering, stealing, or the like, is detected. The signals, which identify the respective vehicles, are stored, and transmitted to a base station, preferably in response to a polling signal. The affected vehicles are immobilized by means of a signal from the base station, or from one of the security stations, at an appropriate time or location. The vehicle's lights may be turned on and its hooter sounded. When the vehicle is not used within range of a security station its security station may be monitored by means of a portable receiver.