Seven people were killed and 15 others injured in an accident in northwest China's Xinjiang Uygur Autonomous Region on Friday, Xinhua reported. The accident took place on a highway in Gongliu County of Yili Prefecture shortly after midnight Friday. According to an official with the Yili prefectural government, a cement truck rear-ended a tractor sending it into the opposite lane. The tractor then smashed head-on with a minibus carrying 24 people. Seven people on board the bus were killed. Fifteen were injured, two seriously. Officials said everyone on board is related. The minibus was over capacity. It was only designed to carry 14 people. The cause of the crash is under investigation.