Authorities have discovered a mass grave in southern Vietnam believed to contain remains of communist fighters killed by French colonial occupiers during a failed prison escape, an official said Monday. A woman uncovered 17 sets of remains last Tuesday as she dug a foundation for her house on the former site of a French prison in Luong Hoa Lac village, Tien Giang province, said Vo Van Hung, the village chief. The remains were likely those of communist fighters killed by the French during a failed escape from the prison in early 1949, Hung said. The story of the prison break is well known in the area. Three communist fighters managed to escape, but 17 more were killed and buried in a mass grave, Hung said. The bodies of two others were thrown into a river.