1. An object detection and tracking system of a three-dimensional (3-D) space, the system comprising: a network for interconnecting components of the system; a common reference clock connected to the network and configured to provide time stamps to the components of the system; two or more spatially separated two-dimensional (2-D) sensors connected to the network and having overlapping fields of view of the 3-D space for detecting and 3-D tracking of one or more moving objects in the 3-D space through concurrent time-stamped 2-D observations, each point in the 3-D space being observable by at least two of the 2-D sensors; at least one image processor connected to the network and for converting each 2-D sensor's time-stamped 2-D observations into time-stamped 2-D spatial characteristics and for extracting 2-D feature data of the one or more moving objects; at least one tracking processor connected to the network and for combining the time-stamped 2-D spatial characteristics and the 2-D feature data from respective said 2-D sensors into time-stamped 3-D spatial characteristics through triangulation and then fusing the time-stamped 3-D spatial characteristics and the 2-D feature data from the respective 2-D sensors into 3-D tracks comprising 3-D kinematic data, and into 3-D feature data of the one or more moving objects; and at least one behavior analysis and alert processor connected to the network and for analyzing the 3-D kinematic and feature data and generating appropriate alerts corresponding to 3-D behaviors of interest.