Nine school children were killed and 20 injured when they were run over by a speeding vehicle in Bihar's Muzaffarpur district on Saturday afternoon, police said.According to district police officials, the incident took place near a school under Minapur block.Muzaffarpur Senior Superintendent of Police Vivek Kumar said the speeding vehicle mowed down the children when they were crossing the road. All the injured children were admitted to a hospital in Muzaffarpur. Bihar Chief Minister Nitish Kumar has expressed sorrow and grief over the incident.The state government has announced a compensation of Rs 4 lakh to the next of kin of each victim.