SHIMLA: A minibus swerved off a mountain road into a deep gorge in northern India killing 20 passengers on Friday, police said.

A 12-year-old boy was the lone survivor, after the bus rolled down into the 500-foot (152-metre) deep gorge in the state of Himachal Pradesh, a senior police officer said.

“The bodies of 20 people have been found. There is just one survivor,” police deputy superintendent Khajan Singh told AFP.

The condition of the young survivor was not immediately known.

The accident occurred in the remote Sangrah area of Sirmaur district, some 150 kilometres (90 miles) from the state capital Shimla.

The bus smashed into pieces and some of the bodies were mutilated beyond recognition, the Press Trust of India reported.

Search operations were hampered by thick grass and the slopes had become slippery after rain, the news agency said.

Bus crashes with double-digit death tolls are all too frequent in India as a result of treacherous roads, speeding vehicles and reckless drivers.

In May, 33 people died in a bus crash near the state's popular summer resort of Kullu.

Some 110,000 people were killed in road accidents in 2011 — more than 300 every day — according to the latest available statistics from the National Crime Records Bureau.