Updated

Police say a series of small explosions erupted across the capital of an east Indian state hours before the main opposition's prime ministerial candidate was to give a campaign speech in a nearby park, injuring at least four people.

Bomb disposal and forensic teams are investigating at least five small blasts Sunday in central Patna. Local media reports say several unexploded bombs are being defused.

Patna district police chief Manu Maharaj says the first blast came from a crude bomb that injured one person when it exploded in a public toilet building on an isolated railway platform. Another bomb reportedly went off near a movie theater.

Thousands were in Bihar's capital for a campaign rally by Narendra Modi, the prime ministerial candidate from the Hindu nationalist Bharatiya Janata Party.