At least three people have been killed and more than 50 others injured after a private bus veered off a mountain road and overturned in northern India, police said Thursday.

"The bus overturned after it skidded off the road Wednesday night. While three people died on the spot, all the injured have been hospitalised. Seven of the injured are said to be in serious condition," a police official said.

Eye-witnesses told cops that the accident occurred after the driver lost control over the speeding vehicle while negotiating a sharp bend.

"However, several lives were saved due to a crash barrier at the site which prevented the bus from plunging into a gorge," local police chief Monika Bhutungru told the media.

A probe has been ordered into the incident, she added.