An eight-year-old boy and his mother were killed in southern Mexico after being swept away in a river during Tropical Strorm Barry, bringing the death toll from the storm to three, authorities said on Sunday. The pair were among a group travelling in a van that was swept away by the swollen river in a town in Oaxaca state. The third fatality occurred in Veracruz, where the storm made landfall on Thursday. A man died while trying to cross a river on horseback and was dragged by the force of the current.