Random sensor deployments following Poisson or Gaussian distribution are the most widely adopted deployment strategies for hostile and unpredictable application scenarios such as environment surveillance and malicious mobile target detection. In the literature, researchers assume either Poisson distributed or Gaussian distributed sensors in modeling wireless sensor networks for performance evaluation. This paper instead examines the performance of a wireless sensor network that employs a hybrid random sensor deployment where a set of the sensors are deployed following Poisson distribution and others follow Gaussian distribution around hot spot(s), which are more important than elsewhere and require higher surveillance and target detection capability. The performance of the hybrid wireless sensor network is evaluated in terms of surveillance and target detection probability theoretically and by simulations. The simulation outcomes match with the theoretical results.