Nine people have been killed and at least 20 others were injured after a bus crashed through a guard rail and tumbled off a highway in northwest China's Gansu province, Xinhua reported. The accident happened around 11 a.m. Sunday on a highway near Tongwei County in central Gansu. The bus suddenly veered off the road and plunged ten meters, according to local traffic policeman Jia Haifeng. Jia said the accident happened only about 200 meters away from their station and they all heard the noise. We were able to carry out an immediate rescue effort, but casualties are still severe, he said. Seven people died at the scene and two others died after emergency medical treatment failed. At least 20 others were taken to hospital. The coach was heading from Tianshui City in southeastern Gansu to Lanzhou, the provincial capital. Local police are confirming identities of the passengers and an investigation has been started into the cause of the accident.