NEW DELHI, June 1 (Xinhua) -- At least seven people were killed and 20 others injured Friday after a passenger bus skidded off mountainous road and fell into a gorge in northern Indian state of Himachal Pradesh, police said.

The accident took place near Theog in Shimla, the capital city of Himachal Pradesh.

"Today a bus belonging to state-run Himachal Road Transport Corporation (HRTC) rolled down a hill near Theog here and in the mishap seven people were killed and 20 others injured," a police official posted in Shimla said.

"The injured were removed to hospital, where the condition of some of them is stated to be critical."

Preliminary investigations carried out by the police said the mishap occurred as the driver failed to negotiate a curve on the road.

Reports said there was maintenance work going on the stretch of road.

According to officials the bus was ferrying local passengers to a nearest town.

Deadly road accidents are common in India often caused due to overloading, bad condition of roads and reckless driving.