Police opened fire on a violent demonstration by members of one of India's lowest castes Saturday, killing four protesters and taking the death toll in two days of protests to 20, a senior police official said.

Gujjars began protesting Friday in villages and towns across Rajasthan state in western India after the government refused to reclassify their caste at a lower social level. Reclassification would allow the Gujjars to qualify for government jobs and university places reserved for such groups.

On Saturday, police in Sikandra town fired at protesters who had torched a police station and two buses and shot and wounded a policeman, said Amanjit Singh Gill, Rajasthan state director-general of police. Protesters also burned a police station in the nearby village of Chandra Guddaji, Gill said.

Thousands of people were meanwhile stranded because protesters were blocking major highways linking the state capital Jaipur to Agra — site of the world famous Taj Mahal monument — and to the national capital, New Delhi.

At least 20 people have been killed in the two days of violence, Gill said.

Fifteen protesters died Friday when police fired live ammunition and tear gas to halt riots in six Rajasthan villages, said Rohit Kumar Singh, the state information commissioner.

Protesters beat a police officer to death in Bharatpur district, Singh said.

At least 26 people died in Gujjar riots in the same area last year.

Thousands of army, police and paramilitary forces patrolled the affected villages to control violence. Authorities stopped nearly 400 tourist buses and diverted trains to Mumbai, India's financial and entertainment capital, Singh told The Associated Press on Saturday.

The protesters uprooted a one-mile stretch of rail track on Friday, leading to the cancellation of nearly a dozen trains, Singh said.

Gujjars took to the streets after a government panel set up to look into their demands recommended a US$70 million aid package for their community, but ruled out caste reclassification.

Gujjars are considered part of the second-lowest group, known as Other Backward Classes, a step up from the Scheduled Tribes and Castes.

The Hindu caste system was outlawed soon after independence from Britain in 1947, but its influence remains powerful.