MEXICO CITY - A bus passenger has killed four robbers on a highway near Mexico City and their bodies were later found on the road by police, authorities said. The thieves boarded the bus near San Pedro Tultepec, pointed their guns and robbed the passengers, the prosecutor's office in the central State of Mexico said in a statement, citing witnesses. As the assailants were leaving, "one of the passengers stood up and began to shoot," the statement said. The bus then headed to Mexico City but the shooter left and was not seen again, prosecutors said.