This letter addresses the problem of target localization in adverse non-line-of-sight (NLOS) environments. By utilizing integrated received signal strength (RSS) and time of arrival (TOA) measurements, a novel alternating algorithm is proposed. The new algorithm is derived by converting the original non-convex problem into a generalized trust region sub-problem (GTRS) framework, which can be solved exactly by just a bisection procedure. Therefore, the proposed algorithm is very light in terms of computational cost, and its excellent estimation accuracy is validated through computer simulations.