Since congestion is very likely to happen in the Internet, locating congested areas (path segments) along a congested path is vital to appropriate actions by Internet Service Providers to mitigate congestion. We propose a practical method to locate congested segments by actively measuring end-to-end packet losses on appropriate paths from multiple origins to multiple destinations, using a network tomographic approach. Then we conduct an experiment performing active measurements of packet losses on multiple paths over the Japanese commercial Internet. The results of the experiment indicate that the proposed method is able to precisely locate congested segments.