Shimla, Aug 21 (IANS): At least 23 people were killed and 20 injured in Himachal Pradesh Thursday when an overcrowded mini bus skidded off the road and fell into the Baspa river, some 300 feet below the road, officials said.

They said the death toll could rise as some of the passengers had received serious injuries in the accident in Kinnaur district.

The private bus, carrying over 40 passengers, was on its way from Sangla to Kalpa. It met with the accident near Sangla, some 300 km from here, Deputy Commissioner D.D. Sharma told IANS from the spot.

He said 11 injured passengers were airlifted to the Indira Gandhi Medical College and Hospital in Shimla. The cause of the accident is yet to be ascertained, he said over the phone.

Superintendent of Police Rahul Nath said after the bus rolled down the hill it landed in the Baspa river, a tributary of the Satluj.

Witnesses said police had a tough time extricating the bodies from the mangled remains of the bus. They said the condition of the road where the accident occurred was bad owing to the recent rains.

People in the area began rescue operations even before the district authorities reached the spot. Most of the victims were from Kinnaur district.

Police said the driver and conductor of the bus were among the dead.

Chief Minister Virbhadra Singh and former chief minister Prem Kumar Dhumal expressed shock and grief over the accident.

The chief minister directed the district administration to take all possible measures to rescue the survivors and provide them adequate relief.

Kinnaur is one of the remotest places in the state. Buses plying there have poor frequency and this scarcity of means of transport often leads to overcrowding of vehicles.

This is the second major accident in the state in less than a month.

Twenty one passengers were killed and five injured July 29 when a state roadways bus fell into a gorge in Shimla district.

Police records say over 800 people die every year in Himachal Pradesh in road accidents. Police have identified 556 accident-prone spots, including 210 on national highways.