One of the main objective of wireless sensor network is to forward the events to the destination in a fast and reliable manner. There are several methods are existing for packet forwarding. Some researchers use single node to forward event packet and some researchers use all nodes (nodes in event region) to forward event packet. In this paper we proposing a technique named as Reliable Event Transmission Protocol (RETP) in a wireless sensor network for real time event detection and reliable packet forwarding in wireless sensor networks. In RETP, we introduce the concept cluster heads to forward the event when event occurred. Here number for event forwarding nodes is restricted by n/2(for even number of nodes) or n-1/2(for odd number of nodes). So it helps to energy conversion, computation cost in the network as well as it ensures the reliability in event forwarding. The literature survey has been done on various techniques in event detection.