Two persons were killed and many injured as violence gripped parts of India on Monday as Dalit groups enforced a day-long country-wide shutdown against a Supreme Court order they say dilutes a law to prevent atrocities against the marginalized Scheduled Castes and Tribes.

The government, in a bid to pacify the agitated Dalit activists, said it had filed a petition in the apex court seeking a review of its March 20 order that bars automatic arrest and registration of cases for alleged harassment of Dalits and others.

Protesters clashed with police in Punjab, Rajasthan, Jharkhand, Madhya Pradesh, Uttar Pradesh, Uttarakhand, Bihar and Odisha -- states where normal life was paralyzed in varying degrees amid incidences of violence and arson.

Clashes turned deadly in Madhya Pradesh where two persons were killed and dozens injured, forcing authorities to impose curfew at many places.

Police said one person was killed in Bhind and the other in Morena.

Gwalior District Magistrate Rahul Jain told IANS that at least 22 persons were injured, some critically, in clashes in his district, where prohibitory orders banning large gatherings were also imposed.

Protesters blocked rail tracks and set fire to vehicles, with plumes of fire and smoke seen on near barren roads.

The Madhya Pradesh government called the Army to control the situation in Bhind, Morena and Gwalior.

Punjab and Haryana also saw widespread protests.

Shops, educational institutions and other establishments remained closed and Class 10 and 12 examinations were deferred in Punjab, which has the highest concentration of Scheduled Castes, constituting nearly 32 per cent its 2.8 crore population.

Hundreds of protesters carrying swords, sticks, baseball bats and flags forced shopkeepers and other establishments in Jalandhar, Amritsar and Bathinda to shut down.

Protests also took place in Rohtak and other towns of neighbouring Haryana.

In Bihar, activists disrupted rail and road traffic. Mobs shut down markets and shops as well as educational institutions, police said.

Supporters of the Bhim Army and other Dalit outfits halted over three dozen long-distance and local trains, stranding thousands of passengers.

"Train services have been badly disrupted due to the protest," an East Central Railway official told.

Violence was reported from Vaishali, Muzaffarpur, Nawada, Patna and Bhagalpur when protestors clashed with police.

Violence also erupted in parts of Uttar Pradesh as protesters attacked shops, looted some and pelted stones at police in Hapur, Agra, Meerut and Saharanpur.

Many cars were targeted and their window panes smashed. At some places, government property was targeted.

Some people reportedly fired at a police team in Meerut while a passenger bus was set on fire. Pro-reservation groups indulged in vandalism at the Muzaffarnagar railway station, stoning the Kocchi Express.

Also in Meerut, over 500 Dalit youths targeted the media and broke their cameras as they were trying to photograph the protests.

Amid widespread anger and violence, the government filed a review petition in the Supreme Court to seek recall of its judgment that ruled that there would be no automatic arrest of an accused following a complaint moved under the Scheduled Castes and Scheduled Tribes (Prevention of Atrocities) Act, 1989.

The Supreme Court had held on March 20 that police will hold an inquiry to ascertain the veracity of the complaint filed under the act before acting on it.

Union Law Minister Ravi Shankar Prasad said the government "with due respect, does not agree with the reasoning given by the apex court".

He said senior government lawyers "will argue this matter with all their legal preparations and authority that this judgment needs to be reconsidered".