This document proposes a local monitoring approach to minimize transmission delay and energy consumption in wireless sensor networks used for critical event monitoring. The network is divided into groups, each with a local monitoring node. When an event occurs, information is sent to the local monitoring node and then to the central node. It is then broadcast to all nodes through the local monitoring nodes. This two-path transmission and use of local monitoring nodes aims to reduce delay compared to sending directly to the central node. The local monitoring approach, sleep scheduling, and wakeup patterns are described to efficiently transmit alarm messages while minimizing energy usage.