At least four persons were killed and 14 others sustained injuries in a road mishap in northern India Wednesday, a senior police official said. 'The mishap happened when an overcrowded vehicle in which the victims were traveling skidded off the road and plunged into a deep gorge near Chirgaon in the hilly town areas of Shimla in the state,' the official said. Road accident rate in India is among the highest in the world with at least 100,000 killed on the road each year. 