A gun battle between supporters of India's ruling right-wing party and a regional rival has killed four people in West Bengal, police said yesterday, as violence raged in the tinderbox state. At least 18 others were injured in the clashes that broke out Saturday in the eastern state that has been on edge since Prime Minister Narendra Modi's Bharatiya Janata Party (BJP) launched an aggressive campaign to win parliamentary seats last year.

"Three of the dead were BJP workers, while the other was a [regional] Trinamool party supporter," a police official told Agence France-Presse (AFP).

Violence peaked across the state during the general election in April and May, and has continued even after the results were announced, giving a massive nationwide victory to the BJP. Both the BJP and Trinamool, led by the firebrand Modi critic Mamata Banerjee, accuse each other of killings, intimidation and corruption. Sandeshkhali, the site of the latest gun battle, remained tense on Sunday with more than 100 police personnel standing guard in the area, witnesses told AFP.

The BJP, which has traditionally held sway in the Hindi-speaking belt in the north, has been trying hard to pick up support in West Bengal where Banerjee's party has dominated for close to a decade. It won 18 seats in the general election in West Bengal, up from the two that it managed in 2014, en route to its nationwide win. Trinamool won 22, while the center-left opposition party Congress picked up two of the total 42 seats in the state. Political killings are rife across India. While National Crime Bureau data said there were more than 100 political murders in 2016, experts say the figure was likely much higher. Kerala, Uttar Pradesh and Bihar states are the worst for political murders, the government data shows.