Authorities say a seven-year-old boy has been killed and 9 other people were wounded in a bomb blast in suburban Kolkata in India's eastern West Bengal state.

Barrackpore Police Commissioner Rajesh Kumar Singh says an investigation is underway into Tuesday morning's blast outside a shop closed on the Indian national holiday for Mahatma Gandhi's birthday.

The impact of the blast ripped through the shop's iron shutters.

Ten people standing outside the shop were injured by debris and taken to a hospital, where the boy died.

Local Trinamool Congress party (TMC) leader Panchu Gopal Roy says he was the target of the explosion.

In late August, nine people were killed in clashes in the state triggered by opposition parties contesting the victory of the ruling TMC party in recent local municipal elections.