Authorities deployed hundreds of riot police and cut mobile internet services in parts of eastern India on Sunday after violent clashes erupted in at least eight states during a Hindu religious festival.

Police said one person was shot dead in the Nalanda district of Bihar state on Saturday after majority Hindus and minority Muslims clashed in the town of Biharsharif.

This came a day after mobs fought running battles and set fire to homes and shops during at times frenzied public celebrations of Ram Navami.

Hindu festivals regularly feature hundreds of people -- sometimes brandishing swords, guns and tridents -- provocatively marching through Muslim neighbourhoods with religious music pulsating through powerful sound systems.

Biharsharif police chief Shibli Nomani said nearly 100 people have been detained over violence that erupted on Thursday when thousands of Hindus rallied on the streets and paraded through Muslim-dominated areas.

"The situation is under control. We are patrolling the area and ensuring no gatherings are allowed," he told AFP, adding that the unrest was being investigated.

Similar communal flare-ups were reported in two other cities in Bihar, where authorities shut mobile internet services in some areas and clamped down on public movement.

In Rohtas, another district hit by violence where police arrested dozens, six people were injured in an explosion inside a house where two men were allegedly making a bomb.

Bihar police tweeted that at first glance it did not appear that the blast was related to the recent unrest. Homemade explosives are sometimes used in mining in the area.

Sectarian violence also hit seven other states in recent days following the Hindu festival on Thursday, with dozens injured and hundreds arrested in at least 13 towns and cities.

This included Uttar Pradesh, Madhya Pradesh, Karnataka and the Howrah region of the eastern state of West Bengal where mobs rampaged and torched vehicles and shops on Thursday.

West Bengal Chief Minister Mamata Banerjee accused Prime Minister Narendra Modi's Hindu-nationalist Bharatiya Janata Party of orchestrating the violence. The BJP accused her of targeting Hindus.

Similar violence was reported in Modi's home state of Gujarat on Thursday in western India where clashes were reported in Vadodara along with Aurangabad in the western region of Maharashtra.

Critics say that hardline Hindu groups have been emboldened since Modi, who was Gujarat state chief minister during huge riots there in 2002, was elected prime minister in 2014.

Last year, similar clashes were reported across several cities on Ram Navami, including in New Delhi and in Jharkhand in eastern India where one person was killed.