Two crashes involving 13 vehicles occurred back-to-back just hundreds of feet apart in southwestern China Saturday, killing a dozen people, authorities said. Three people died and two were injured in the first crash when a truck crashed into the rear of a car just after 4 p.m. on an expressway in Yunnan province, police told Xinhua News Agency. About 15 minutes later, nine people were killed and 17 were injured when 11 vehicles piled up about 400 feet away. The cause of the crashes had not been determined, Xinhua said.