Hi Biswas,
You have several options here. You can try the Detect and Track Multiple Faces example on the File Exchange, which detects and tracks multiple faces. You can try the same thing: replacing vision.CascadeObjectDetector with vision.PeopleDetector.
Alternatively, if your camera is stationary, you can use vision.ForegroundDetector to detect any moving objects. See Motion-Based Multiple Object Tracking example in the Computer Vision System Toolbox.
In either case, if you want to track people reliably for 10-15 minutes, you will have to do a lot of tweaking and tuning of parameters.
