'We have seen 10 bodies ourselves,' said Satish Joshi, a leader for the Uttarakhand Sangharsh Samiti, after police fired on a 7,000-strong crowd at Muzaffarnagar, 150km (90 miles) from Delhi. 'Some 160 people were injured in all, and thousands are blocking the highway to Delhi,' he said.
The protesters were calling for the creation of a separate Himalayan hill province, that they want to call Uttarakhand.
A P Singh, a senior official in the home department of the government of the northern state of Uttar Pradesh, said only four people were brought dead to a government hospital in Roorkee town, about 50km from Muzaffarnagar. The demonstrators were heading towards Delhi for a planned rally behind the Indian capital's Red Fort, when they were stopped, officials said.
Police fired as violence broke out after a police baton charge failed to turn back the demonstrators. Police arrested 350 people but they were released later in the day, Mr Singh said. Officials in Lucknow, the capital of Uttar Pradesh, said that the protesters staged a sit-in on the main road to Delhi after the police opened fire, and blocked the traffic.
The rally in Delhi, whose organisers claimed 300,000 people were there, although reporters estimated the number to be about one-fifth of that, started in chaos when students tried to throw politicians off the stage.
The students, who have been the main driving force for a new state, said they did not want the movement politicised. They objected to the presence on the stage of members of the ruling Congress Party and the opposition Hindu nationalist Bharatiya Janata Party.