1. A method comprising: receiving a first input from a first sensor at a first sensor node of a wireless ad hoc network; receiving a second input from a second sensor at the first sensor node, wherein the second sensor is separate from and external to the first sensor, and wherein the first sensor node comprises the first sensor and the second sensor; comparing the first input to a first predefined input threshold associated with an intrusion activity at the first sensor node; comparing the second input o a second predefined input threshold associated with the intrusion activity; and wirelessly communicating an indication of the intrusion activity from the first sensor node to a gateway device via a second sensor node of the wireless ad hoc sensor network, wherein the gateway device comprises an interface between the wireless ad hoc sensor network and a user-interactive system configured to monitor the wireless ad hoc sensor network.