Monday's accident occurred in Almora district in the mountainous state of Uttarakhand.
The bus was carrying around 60 people and more than 20 have been injured, said Vineet Pal, a state government official.
Authorities said earlier they believed there were 42 passengers, which was how many people the bus could accommodate.
Teams of rescue and relief workers were deployed to the site and authorities said the death toll may rise as they work to rescue passengers who may still be trapped inside.
An injured person is taken to hospital in Uttarakhand's Almora District. (EPA PHOTO)
The state's chief minister, Pushkar Singh Dhami, said teams were working to evacuate the injured passengers to the nearest health centre for treatment and that authorities have been instructed to airlift those seriously hurt.
A preliminary investigation suggested the bus, which was reportedly in a dilapidated condition, skidded before tumbling down a 60m-deep gorge, Pal said.
Dhami said on X that an investigation would be carried out into the cause of the incident.
जनपद अल्मोड़ा के मार्चुला में हुई हृदयविदारक बस दुर्घटना में अपनी जान गंवाने वाले यात्रियों के परिजनों के प्रति हमारी गहरी संवेदनाएं हैं, दुख की इस घड़ी में हम उनके साथ खड़े हैं। ईश्वर से घायलों के शीघ्र स्वास्थ्य लाभ और दिवंगतों की आत्मा को श्रीचरणों में स्थान प्रदान करने के लिए… — Pushkar Singh Dhami (@pushkardhami) pic.twitter.com/VeFrEmVGxANovember 4, 2024
A number of passengers managed to escape or were thrown out by the impact, and then alerted authorities about the accident.
India has some of the highest road death rates in the world, with hundreds of thousands of people killed and injured annually. Most crashes are blamed on reckless driving, poorly maintained roads and aging vehicles.
In July, at least 18 people died after a double-decker passenger bus collided with a milk truck in Uttar Pradesh state. In May, a bus carrying Hindu pilgrims skidded and rolled into a deep gorge on a mountainous highway in Indian-controlled Kashmir, killing at least 21 people.
with Reuters