At least 24 people were killed and 22 others injured on Tuesday when the passenger bus they were travelling in plunged some 300 metres down a steep hillside in eastern Nepal's Khotang district.The bus was travelling to capital Kathmandu from Kavrepani Bhir.Furgel Sherpa, police inspector at Khotang district, said all the victims have been identified.The injured were airlifted to Kathmandu for treatment. However, the exact number of passengers travelling in the bus was not immediately known and the cause of the accident was under probe.