Gunmen on motorbikes in India’s West Bengal ambushed and killed a political aide from the ruling Hindu-nationalist party days after it swept state elections, police said Thursday.

Prime Minister Narendra Modi’s Bharatiya Janata Party (BJP) won a resounding victory on Monday in the eastern state of more than 100 million people, taking 207 of the 294 assembly seats, for its first-ever state victory in West Bengal.

Chandranath Rath, 41, a close aide of West Bengal’s BJP chief Suvendu Adhikari was shot dead late on Wednesday near his home in Kolkata.

Adhikari, the leader of the opposition in the state assembly, now tipped to become the state chief minister, called it “cold-blooded murder”.

Motorbikes blocked Rath’s vehicle, before the attackers opened fire in a barrage of around a dozen shots, hitting Rath multiple times in the heart.

“The shooting happened at about 11 pm on Wednesday — the bikes that stopped Rath’s car have been seized,” West Bengal police chief Siddh Nath Gupta told AFP.

“The bikes had fake registration numbers, and we are looking for the assailants.”

Pritam Sengupta, a doctor at Apollo Hospital told AFP, that Rath was “brought dead with multiple bullet injuries in his chest.”

The killing brings the total killed since the results were announced on Monday to at least five.

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), also lost her seat in the polls and has rejected the results.

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.

The killing has added to political tensions in the state, with the BJP and TMC trading accusations over the deaths since the results.

“It was a planned murder,” BJP’s West Bengal president Samik Bhattacharya said.

“This is expected from Trinamool Congress,” he alleged. “They are responsible for this death”.

The TMC rejected any role in the shooting, but accused the BJP of targeting their supporters.

“We strongly condemn the brutal murder of Chandranath Rath,” the party said in a statement, adding that it also condemned attacks on TMC members “allegedly carried out by BJP-backed miscreants”.

The BJP said it will swear in its leader as chief minister on Saturday.