The impact of the fall was so huge, the bus was broken into pieces, a police official said.
Going from Rishikesh to Ghat, the bus fell off a steep slope on Nandprayag Ghat motorway into a 300 metre-deep gorge at about 12.45pm, when it was around half a kilometre away from its destination, he said.
Five injured persons were being treated at district hospital in Chamoli, he said, adding 22 people, mostly villagers from Ghat block, were on board the ill-fated bus, he said.
Uttarakhand chief minister Harish Rawat and Governor Aziz Qureshi expressed deep shock over the tragic mishap saying so many precious lives were lost in the accident.
Wishing the injured a speedy recovery, Rawat asked officials concerned to make all facilities available for the treatment of the injured admitted at district hospital Chamoli.
The bus was owned by Garhwal Motor Owners Company. Most of the passengers of the bus are said to have been hailing from Ghat block, the official said.