At least 21 people were injured Saturday in violent clashes between Sri Lankan government supporters and villagers marching against what they say is a plan to take over private land for an industrial zone in which China will have a major stake. Police used tear gas and water cannons to try to break up the clashes, which took place as Prime Minister Ranil Wickremesinghe was attending an opening ceremony for the industrial zone, located near the port city of Hambantota, about 150 miles southeast of the capital, Colombo.