According to international media, the vehicle was travelling along a treacherous mountain highway in Uttarakhand state’s Pauri Garhwal district on Tuesday evening when it careened over the edge and plunged at least 500 metres (1,640 feet) with about 45 people onboard.
“Twenty people have been rescued,” said the state’s top police official Ashok Kumar.
Prime Minister Narendra Modi said that “all possible assistance” would be given to the survivors. “In this tragic hour my thoughts are with the bereaved families,” he tweeted.
Fatal road accidents are common in Uttarakhand, which encompasses part of the Indian Himalayas and is home to numerous religious pilgrimage sites.
Nearly 24 people were killed in June when their bus plunged into a gorge while en route to a shrine to the Hindu deity Yamuna, north of the state capital Dehradun.
More than 110,000 people are killed every year in road accidents across India, according to police. The accidents are caused by reckless driving, poorly maintained roads and ageing vehicles.