The present invention provides an alert system for providing protection to the users inside the vehicle from potential intruders and ambushers. The alert system includes a proximity detection unit using microwaves to detect any potential ambusher in the vicinity of the vehicle, an alarm unit raises an alarm to alert the users of the vehicle of the potential ambusher(s), a warning unit to warn the potential ambusher to back away and a remote communication unit to broadcast a signal to a remote location to inform the personnel therein about the potential attack. The alert system also includes means to mitigate false alarms. Further, the alert system is capable to be retro-fitted into existing vehicles.