At least 13 people were killed on early Saturday after an 18-wheeler and a passenger bus crashed into each other in Mexico's Gulf Coast state of Veracruz, media reported.Initial police reports said the crash occurred around 3:30 a.m. (0930 GMT) along the Mexico-Veracruz Highway, outside the town of Rancho Viejo.The bus burst into flames upon impact with the double trailer semi truck, which was carrying railway sleepers, Xinhua quoted daily La Jornada as saying.Only one person survived by exiting through a window, the daily said.The bus had departed from Mexico City and was heading for Villahermosa, the capital of southeast Tabasco state.Witnesses said the driver of the trailer truck fled the scene.Authorities from the Veracruz prosecutor's office visited the site of the accident to begin an investigation.