KOLKATA, May 4 -- Vote counting in key Indian state elections was underway today under tight security, with the focus on West Bengal, where Prime Minister Narendra Modi's party is hoping for crucial gains.

Elections in five states and territories took place in April and May, and Modi's Bharatiya Janata Party (BJP), the ruling party in the national parliament, is hoping to make inroads into opposition-held states.

In West Bengal, the Hindu-nationalist BJP waged an aggressive bid to dislodge Chief Minister Mamata Banerjee, the firebrand leader of the All India Trinamool Congress (TMC), in power in the state of 100 million people since 2011.

Exit polls last week predicted the BJP has a slight edge over TMC, although exit polls have a patc...