Three persons were killed and 21 others injured when a bus fell into a gorge at Nichupu in East Kameng district of Arunachal Pradesh on Thursday.The bus was going to Seppa from Tezpur in Assam, sources said adding that 12 of the injured have been rushed to Tezpur for treatment.Arunachal Pradesh government has announced ex-gratia of Rs one lakh for the next of kin of each deceased and Rs 10,000 to Rs 50,000 for the injured.