Complex Event Processing (CEP) is a technique for analyzing streams of event data in real-time, improving situational awareness and enabling immediate response to emerging opportunities and threats. Kalman Filter is a widely used technique for prediction. Kalman Filter is very useful for tracking people/objects. This paper presents an efficient tracking system that tracks multiple people simultaneously in an intelligent way. An integrated system of Complex Event processing (CEP) and Kalman tracking is used for tracking the persons who appears to be intruder. Data or events are generated when the person is sensed by sensors. Data generated in a WSN environment has lot of noise, redundancy, and missing information. The proposed system addresses all these issues by using CEP, a knowledge base and Kalman tracking. © 2011 IEEE.