A series of blasts ahead of an opposition candidate's rally in an eastern Indian city left five people dead and 83 wounded, as campaigning kicked off for India's national election next summer.
At least six crude bombs exploded near a public ground in Patna where tens of thousands of people had gathered on Sunday to hear Narendra Modi as he took his campaign to the big heartland state of Bihar.
"There was a blast right behind me. I heard people saying that one of the tyres of a vehicle has burst," said a witness. "When I went to the spot, I saw many people lying injured on the ground."
Television channels showed pictures of shattered windows of buses, smoke billowing and people running in panic.
It was the first outbreak of violence since Modi, the challenger from the Hindu nationalist Bharatiya Janata Party, began an aggressive campaign to oust the ruling Congress-led coalition.
To his critics Modi is a deeply polarising figure under whose watch Muslims were attacked in deadly rioting in 2002 in the western state of Gujarat, which he has governed for three straight terms.
But to his growing army of supporters, including many in Indian business, the BJP leader is the best hope the nation has of turning around the economy after helping make Gujarat one of the country's fastest growing states.
Modi himself has denied any allegations of bias against Muslims and a Supreme Court-appointed panel cleared him of any wrongdoing in the riots. On Sunday, he sought to broaden his appeal, saying Hindus and Muslims both needed to be lifted out of poverty.
"Do you want to fight against poverty or against Hindus?," he asked. "Poor Muslims have to fight against poverty. Poor Hindus have to fight against poverty."
Modi did not mention the blasts in his speech, but later called them "deeply saddening and unfortunate" on Twitter. He appealed for peace and calm.
Police inspector general Sushil M Khopde said five people were killed in the blasts. Three unexploded bombs were found at the venue of the rally.
No one has claimed responsibility for the blasts. However, police say they have detained some people for questioning.