KOLKATA - An improvised bomb exploded in eastern India Friday, killing two people who had been making explosives in a cow shed, a senior police official said.

The explosion took place in Birbhum district of West Bengal, about 200 kilometres (124 miles) west of state capital Kolkata. “Two people were killed when the bomb they were making exploded in a cow shed in their home at Khairasol early today,” police inspector general Anuj Sharma told AFP. “A big police contingent has rushed to the spot. We are investigating the incident.”

The episode comes amid tightened nationwide security ahead of the annual Republic Day on Tuesday, when the country marks the anniversary of India’s democratic constitution taking force in 1950 with colourful festivities. Sharma said the tin roof of the shed was blown away by the impact of the explosion.

West Bengal, one of India’s largest states, has been wracked by separatist and communal violence for decades.