Nine people were killed and five injured Sunday when a minibus fell off a cliff in China's Guangxi Zhuang autonomous region, authorities said.The accident happened at about 3 p.m. in Du'an Yao autonomous county in Hechi city when 14 people aboard the eight-seat minibus were travelling on a mountain road in rain, Xinhua quoted the county government as saying in a statement.Four passengers were killed at the scene and five succumbed to injuries in hospital. An initial investigation blamed slippery road and low visibility for the deadly accident.