1. A surveillance system for the detection of an alarm situation, the system comprising the elements of: a video analysis unit for analyzing at least two video data streams recorded by at least two capturing devices, each of the two streams representing images of a monitored area, the video analysis unit comprising an object tracking module for tracking the movements and the location of at least two video objects seen in the at least two video data streams; a detection, surveillance and alarm application for receiving video data analysis results from the video analysis unit, for automatically identifying a first event associated with a first video object in a first video data stream, identifying a second event associated with a second video object a in a second video data stream, and linking the first event and the second event through association of the first object and the second object, and for generating an alarm signal; and an event database for storing the first video object, the second video object, video object parameters, the first event and the second event, wherein tracking the movements and the location of each of the at least two video objects is done by generating difference frames representing the differences between at least two reference frames and another frame from one of the at least two video data streams.