Localization of events is a canonical problem for sensor networks, especially for applications such as intrusion detection or neighborhood monitoring. We employ a general sensor model which models various types of sensor nodes. However, traditional triangulation method will be unsolvable when the sensor nodes are positioned on a line. To overcome such ill-conditioned cases, we can use MAP or MMSE methods to estimate event locations. Moreover, to locate multiple simultaneous events and overcome the illconditioned case when the sensor nodes are colllinear, we need to solve a system of nonlinear equations. We propose a novel method which solves this system of nonlinear equations and multiple-event locations can be found. Experiments and error analysis of the method demonstrate the performance of our methods.