Four people died and four others were wounded near a polling station in Cooch Behar district on Saturday when security forces opened fire to control a crowd, senior police officer Vishal Garg was quoted as saying by The Associated Press news agency.

He gave no further details on what had sparked the clashes.

In a separate incident, unidentified gunmen fired at voters at another polling booth in the same district, killing one person. Garg said police were investigating the attack.

Local elections in West Bengal, India’s fourth most populous state with 90 million people, are being held in eight phases. Voting in four Indian states and a union territory began in late March and is spread over a month. Results will be declared on May 2.

Security arrangements were tightened and nearly 80,000 security personnel were deployed across 16,000 polling stations in West Bengal for Saturday’s voting, reports said.

The Eastern state, which has Kolkata as its regional capital, has been hit by election-related violence before, including deadly clashes between supporters of rival political parties.

The vote is seen as a contest between the state’s ruling All India Trinamool Congress and Indian Prime Minister Narendra Modi’s Bharatiya Janata Party (BJP).

State Chief Minister Mamata Banerjee confirmed Saturday’s deaths, even as the rival parties blamed each other for inciting the violence and demanded a probe by the Election Commission.

The elections are seen as a crucial test for whether the BJP can gain a foothold in the Northeast and south. The Hindu nationalist party controls a dozen of India’s 28 states, with alliance partners in several others, but it has never won power in West Bengal.

Modi and his top leaders have campaigned heavily to wrest power from the Trinamool Congress.

A defeat for Banerjee, a strong Modi critic, would deal a blow to the country’s already weak opposition.

Modi’s overall popularity remains unmatched in India, but his party has faced tougher than expected challenges in recent state polls.