Unrest grips the key eastern state after Modi’s Hindu nationalist BJP wins the state election for the first time.

At least four people have been killed in political unrest after Indian Prime Minister Narendra Modi’s Hindu nationalist party won the state election in West Bengal, police and party officials say.

Modi’s Bharatiya Janata Party (BJP) swept the polls in its first-ever victory in the key eastern state, home to about 100 million people, winning 206 of the 294 assembly seats, according to results announced on Tuesday.

West Bengal had been ruled by Modi’s fierce critic and adversary, Mamata Banerjee, as chief minister since 2011.

Banerjee, leader of the regional All India Trinamool Congress (TMC) party, also lost her seat in the polls and has rejected the results, accusing the federal government of rigging the election.

Police said clashes between rival party supporters erupted in the state capital, Kolkata, and other West Bengal districts after the results were announced.

The BJP said two party workers were killed, while the TMC said two of their workers were beaten to death.

“Two of our workers were killed after results of the elections were announced on Monday,” BJP state leader Samik Bhattacharya told the AFP news agency, insisting that the party stands “for peace”.

TMC, in a statement on social media, reported the “brutal murder” of two party workers.

“Our party offices were attacked in several areas of the state,” TMC spokesman Narendranath Chakraborty told AFP. “Two of the victims were grassroots political workers.”

A senior police officer, who was not authorised to speak to reporters, confirmed four deaths in clashes and said one officer had been shot in the leg.

The TMC also said its offices were vandalised by alleged BJP workers.

Police in Kolkata said a law and order situation arose on Tuesday in parts of Topsia and Tiljala areas, “during which certain miscreants vandalised public property, etc”.

After the election results were announced, Banerjee refused to resign as chief minister. Calling the BJP’s win an “an immoral victory,” Banerjee claimed more than “100 seats were looted by the BJP”.

According to the Indian constitution, ⁠the state’s governor can demand Banerjee’s resignation or wait for her term to expire, after which newly elected politicians would be sworn ⁠in and the process of forming a new government would ⁠begin.

Banerjee’s term is set to end on Thursday.

Meanwhile, the Election Commission of India (ECI), which has denied allegations of misconduct, directed West Bengal’s top officials to enforce “zero tolerance” towards any incidents of post-poll violence.

“The ECI asked the state administration and security agencies to take all necessary steps to prevent intimidation, reprisals or clashes linked to the electoral outcome,” public broadcaster All India Radio reported.

Analysts say the BJP’s victory in the largely Bengali-speaking state is one of its most significant since Modi was first elected prime minister in 2014, expanding its dominance beyond the Hindi-speaking heartland of north and central India.